Why They Sealed the Deepest Hole on Earth
The short answer
To stop things falling in. The Kola Superdeep Borehole, on the Kola Peninsula in the Russian Arctic, reached 12,262 m (7.6 miles), the deepest hole ever dug. After it was mothballed in 1995, the crew built a steel plug themselves so vandals couldn't drop things down it, a brick for example. The plug unscrews, so instruments can go down again.
Hell had nothing to do with it. The story that Soviet scientists drilled 9 miles down and recorded screams was false from the start. A Norwegian teacher then added to it as a prank and attached his real phone number. Nobody called him before it aired.
How the hole to Hell story grew
In 1989 American TV ran a story: Soviet scientists had drilled 9 miles down, and a Doctor Azzacov had lowered a microphone and heard the screams of Hell. The radio host Rich Buhler traced it. TV got it from the monthly magazine of a Finnish Christian group. That came from a reader's letter in a Finnish daily paper, the letter from a newsletter, and that newsletter from one in California, where the trail ended. The place was wrong, the depth was wrong, and there was no such doctor.
Åge Rendalen, a Norwegian teacher, saw the broadcast while visiting California. Back in Norway he clipped a newspaper story about a building inspector. He wrote a made up English translation and labeled the inspector's photo Doctor Azzacov. He added a shining creature with bat wings rising out of the hole. Then he signed it with his real name, address and phone number, and named a pastor friend who was ready to admit the whole thing. Nobody called. They aired it.
Buhler's staff found Rendalen in about 45 seconds through directory assistance. Rendalen told him: “None of it is true. I fabricated every word of it.” Christianity Today reported the story in July 1990.
The famous recording came later. No tape turned up in 1989. Years afterward a listener sent one to a late night radio show and said it came from his uncle, who got it from a friend at the BBC. It is a loop of screaming, run through effects. Nobody has proved where the screams underneath came from.
What the drill really found
Drilling began in 1970. Only the tip turned. Drilling mud pumped down the pipe spun a turbine at the bottom, and the pipe just hung there. The pipe was aluminum alloy, because ordinary steel pipe that long would snap under its own weight. A bit lasted about 4 hours and cut 7 to 10 m. To change it, the crew pulled up all the pipe and put it back. At 12,000 m that took 21 hours. In the final phase the hole grew by up to 60 m a month, which works out to about 2 m (6 feet) a day.
The rock surprised everyone. The plan expected granite, then basalt, where seismic records showed a layer. The basalt never came. The drill stayed in granite type rock, cracked and changed, and that is what had looked like a new layer on the records. Salty water was moving through broken rock deeper than anyone thought water could get. The planners expected about 120 °C (250 °F) near the bottom. They measured 212 °C (over 400 °F).
In June 1979 the hole passed the old record, held by a US well. Drilling paused at 12,066 m for a geology congress in Moscow in August 1984. On 27 September 1984 the pipe broke. The turbine and about 5 km (3 miles) of pipe stayed in the hole. The crew went back up to about 7,000 m and started again. They reached 12,262 m in 1990. The Soviet stamp honoring the hole came out in 1987, three years after the break.
In December 1991 the Soviet Union, the country paying for the pipe, came to an end. Deep drilling stopped in 1992. The hole was mothballed in 1995, and in 2007 a decision was made to take the rig apart. A few oil wells are longer than this hole because they bend sideways, but none has gone deeper straight down. China's Shenditake 1, announced as finished in 2025, reached 10,910 m.
How we know what is deeper
The film draws the hole to scale on a picture of the Earth, and it hides inside the line around the planet. What we know about the inside comes mostly from listening. A huge earthquake knocks on the whole planet, and the planet rings.
The film plays the real thing. Japan's great earthquake of 11 March 2011 was recorded at the Black Forest Observatory in Germany, a seismograph in an old silver and cobalt mine under up to 170 m of rock. We took 33.6 days of that record and kept only the Earth's slow notes. We sped it up 400,000 times and turned up the quiet end, so a month lasts about 7 seconds. Nothing was added.
The steady note you hear is the Earth's breathing mode: the whole planet swelling and shrinking a tiny bit, about once every 20.5 minutes, for weeks. At Kola, seismic records misled the planners about one layer, and the drill went down and checked. Below the hole, waves like these are still mostly how we know what is there.
Key numbers
| What | Number | Source |
|---|---|---|
| Deepest point of the Kola Superdeep Borehole | 12,262 m (7.6 miles) | Lobanov, Chicherov and Sharov, 2021 |
| Width of the drill bit at the bottom | 214 mm (the film says about 9 inches) | Lobanov, Chicherov and Sharov, 2021 |
| Temperature near the bottom, planned and measured | about 120 °C (250 °F) planned, 212 °C (over 400 °F) measured | Lobanov, Chicherov and Sharov, 2021 |
| What one drill bit lasted | about 4 hours, 7 to 10 m (about 23 to 33 feet) | Lobanov, Chicherov and Sharov, 2021 |
| Time to pull up all the pipe, change the bit and put it back, at 12,000 m | 21 hours | Lobanov, Chicherov and Sharov, 2021 |
| Best progress in the final phase | up to 60 m a month, about 2 m (6 feet) a day | Our arithmetic from Lobanov, Chicherov and Sharov, 2021 |
| Left in the hole when the pipe broke on 27 September 1984 | the turbine and about 5 km (3 miles) of pipe | Lobanov, Chicherov and Sharov, 2021 |
| Shenditake 1 in China, the deepest vertical well in Asia | 10,910 m, completion announced in 2025 | Drilling Contractor, 2025 |
| Time it took to find the hoaxer by phone | about 45 seconds | Rich Buhler, TruthOrFiction |
| Voyager 1's distance at one light day, compared with the hole's depth | about 2 billion times farther (16 billion miles against 7.6 miles) | Our arithmetic from Voyager 1, NASA |
| The Earth's breathing note after the 2011 Japan earthquake | 0.814 mHz, about once every 20.5 minutes | Our arithmetic from Global Seismograph Network, station BFO |
| Speedup of the earthquake recording in the film | 400,000 times: 33.6 days become about 7 seconds | Our arithmetic from Global Seismograph Network, station BFO |
What the film simplifies
- The film says the hole is about 9 inches wide. The drill bit at the bottom was 214 mm, a little under that.
- “30 feet on a good run” is the best case. A bit cut 7 to 10 m, and a good month of up to 60 m in the final phase works out to about 2 m (6 feet) a day, as the film also says.
- Mash the ghost, the lemmings, Gravity, Pressure and the picnic are cartoon. The real rig, Uralmash 15000, was ordered taken apart in 2007.
- Rendalen's “Finally!” and Buhler's “About your doctor” are our wording. The phone call and “I fabricated every word of it” are real.
- “Nobody has ever dug deeper” means straight down. A few oil wells are longer, because they bend sideways.
- The Earth's ring is real data, but we kept only its slow notes, sped it up 400,000 times and turned up the quiet end so ears can hear it. Nothing was added.
At a glance
Runtime 14 minutes · Topics: Deep drilling, Inside the Earth, Seismology, Hoaxes and fact checking · Captions on YouTube · Full script below
Test yourself
Why was the deepest hole on Earth sealed?
Answer
After it was mothballed, the crew built a steel plug so vandals couldn't drop things down it, a brick for example. The plug unscrews, so instruments can go back down.
Near the bottom, a bit lasted about 4 hours but changing it took 21 hours. Why did that make the drilling so slow?
Answer
Each bit cut only 7 to 10 m, and then all the pipe had to come up and go back down. One cycle of about 25 hours, more than a day, bought at most about 10 m.
The deepest hole ever dug reached only about 12 km. How do scientists know what is inside the Earth?
Answer
Mostly from seismic waves: a huge earthquake makes the whole planet ring, and the ringing tells us what is inside. At Kola the drill showed that a layer seen on the records was really cracked granite type rock, not basalt.
The script
Read the script
Host: The story on American TV, 1989. Soviet scientists drill 9 miles down. A Doctor Azzacov lowers a microphone.
Host: 17 seconds of tape, people say. Then the microphone melts.
Rocket: Oh, that is awesome.
Mash: You are on my lid.
Rocket: Whoa. Who's the hat?
Mash: Uralmash 15,000. Mash. I dug this.
Rocket: Okay, Hat! 16 billion miles and I never looked down! The hole to Hell? How deep'd you go?
Mash: Cold today.
Rocket: It's the Arctic.
Mash: Yes.
Rocket: 9 miles? I'll beat that by lunch! Or I bolt this lid back on myself!
Host: The deepest hole humans have ever dug is about 9 inches wide.
Rocket: ...That's the first mile.
Mash: Three feet.
Gravity: You went down. On purpose.
Gravity: I brought snacks.
Host: Somebody sealed that hole with a steel plug and a ring of bolts. Everybody has a theory why.
Rocket: Hey. Hat. Pull me out.
Mash: Busy.
Rocket: 15,000. 15,000 what?
Mash: Is name.
Host: His engine points at the sky. So when he fires it, he goes down.
Gravity: Do it again!
Rocket: Is somebody hanging something on me?
Mash: Coat. Lemming coat.
Gravity: Get over here! Bring everybody! He's doing it to himself!
Mash: You have reverse?
Rocket: Reverse? I have confidence. Who digs a hole on purpose anyway? A hole is what you get when flying goes badly.
Mash: Everybody wanted down.
Host: California. Walter Munk's house. A club of top scientists with a joke for a name, at a meal they call a wine breakfast.
Host: And over breakfast, Munk pitches it. Drill through the bottom of the ocean, all the way to the Earth's mantle. Their slogan?
Scientist: The ocean's bottom is at least as important to us as the moon's behind!
Rocket: Who was in charge?
Mash: Wine.
Host: 1961, off Mexico. A barge drills 600 feet into the sea floor. President Kennedy sends a telegram.
Rocket: For 600 feet? I did three! Where's my telegram?
Host: Then the estimate goes from 14 million dollars to past 125. Congress shuts it down.
Mash: Wine.
Mash: Kola. Not Siberia. Everybody says Siberia. No wine. June 1979, I pass everybody. Nobody has passed me since.
Rocket: So how deep did you go?
Mash: Look. Lemming.
Rocket: I'm in a hole!
Mash: Then you will miss it.
Rocket: Big deal. Giant drill, you spin it, you go down.
Mash: No. Watch.
Host: Only the tip turns. Mud pumped down the pipe spins a turbine at the bottom. The pipe just hangs there.
Rocket: The deepest hole on Earth runs on mud?
Mash: Also pipe.
Host: Ordinary steel pipe that long snaps under its own weight.
Gravity: That's me. I do that.
Mash: So we use aluminum.
Gravity: Coward.
Mash: Bit lasts four hours. Cuts 30 feet. On good run.
Rocket: So you pop on a new bit.
Mash: Bit is at the bottom.
Rocket: ...No.
Mash: Pull up all the pipe. New bit. Put back all the pipe. 21 hours.
Rocket: You're taking the house apart to change a lightbulb! Hold on. Four hours digging. 21 hours changing the bit. That's 25 hours.
Mash: Yes.
Rocket: A day has 24.
Mash: Yes.
Host: Near the bottom, one good run took a full day and bought about 30 feet.
Rocket: That lemming just beat you! I do 30 feet by accident! I sneezed once and missed Neptune!
Host: Averaged over a month, it was more like six.
Mash: You did three.
Host: Nearly two months a year the sun doesn't come up here. The crews head out from town in the dark. And the rig growls, day and night. If it ever goes quiet, something has stopped.
Pressure: Who parked a tin can in my ceiling?
Gravity: My cousin! I do this for love. He does it for a living.
Host: The plan said granite, then about four miles down, basalt. The seismic records showed a layer right there.
Mash: No basalt layer.
Rocket: Did you look behind the granite?
Pressure: That layer? Me.
Host: Deep down, more granite type rock, cracked and changed. On the records, it looked like a new layer. Nobody knew until somebody went down.
Host: Salty water, five miles down, moving through the broken rock. Nobody thought water could get that deep.
Rocket: Hell has plumbing!
Host: Tiny fossils, in rock 2 billion years old.
Rocket: Demons!
Mash: Very small. Very dead.
Host: They planned on about 250 degrees Fahrenheit at the bottom. They got over 400.
Rocket: 400 degrees! That's Hell!
Mash: Is oven.
Host: Past 12,000 metres, the end of 1983. They stop digging to get ready for company. August 1984, Moscow, geologists from all over the world, and the minister has a number.
Minister: 12,066 metres!
Host: 31 foreign scientists are invited up to watch him run. They even put him on a stamp. Ten kopecks.
Rocket: You're on a stamp? Okay Hat! 12,000, three to go! You legend! So how deep did you go?
Rocket: No, I said how deep did you...
Host: September 27, 1984. About six weeks after the congress. They start up again. 9 more metres. Then they begin to pull the pipe.
Rocket: Fine! Don't tell me! I had a stamp once! Moon edition! So big they had to lick it with a
Rocket: Mash?
Mash: I pulled.
Mash: It did not come.
Host: The turbine and three miles of pipe stayed in the hole. They went back up to seven kilometres and started again.
Rocket: How long?
Mash: 6 years. To get back.
Host: They printed that stamp three years after the pipe broke.
Rocket: But they heard something. The tape. 17 seconds.
Mash: What tape.
Rocket: Siberia! 9 miles down!
Mash: Is not Siberia.
Rocket: Doctor Azzacov!
Mash: Who.
TV anchor: Scientists have discovered Hell!
Host: TV got it from a small Finnish religious magazine. The magazine got it from a reader's letter. The letter from a newsletter. The newsletter from a California newsletter nobody could ever find. Wrong place. Wrong depth. No such doctor.
Rocket: I bet on 9 miles!
Mash: Yes.
Rocket: You let me!
Mash: You were busy.
Host: Watching in California is a Norwegian teacher named Åge Rendalen. He goes home and picks up the scissors.
Host: He clips a local paper's story about a building inspector.
Host: He makes up an English translation, and labels the inspector's photo Doctor Azzacov.
Host: Then he writes in a shining creature with bat wings, rising out of the hole. It spells out I have conquered, across the sky. In Russian.
Rocket: A bat!
Host: And he signs it. His real name, his real address, his real phone number. Plus a pastor friend, ready to admit the whole thing.
Rocket: Did they call?
Host: Nobody called.
Host: They aired it.
Rocket: They took a story about a building inspector, and put it on TV as the man who found Hell?
Host: It takes a Christian radio host named Rich Buhler about 45 seconds to find him. Directory assistance.
Rich Buhler: Mr. Rendalen? About your doctor.
Åge Rendalen: Finally! None of it is true! I fabricated every word of it!
Host: Christianity Today runs it, July 1990. And the real chief, David Guberman, still spends 20 years swatting it. Abroad, a state governor greets him with this.
Governor: So how are things in Hell?
Rocket: But I heard it! You heard it!
Host: No recording turned up in 1989. Years later a listener sends one to a late night radio show, and says it came through his uncle's friend at the BBC.
Rocket: His uncle's friend?
Host: It's a loop, run through effects.
Host: And nobody has proved where the scream underneath came from.
Rocket: I said awesome to a loop.
Mash: Yes.
Rocket: Okay. But the lid! Nobody seals a hole for nothing! What got out? Is it demons?
Host: 1995. The money's gone, the hole is mothballed, and scavengers come. So the crew builds that plug themselves. And the last director has told reporters exactly why.
Rocket: Why?
Mash: Brick.
Rocket: Brick?
Host: To stop vandals dropping things down it. A brick, for example.
Rocket: But the red glow!
Mash: Also, it unscrews. In case somebody comes back.
Rocket: It unscrews? I blew it off with fire! Who'd be dumb enough to go down a 9 inch hole anyway?
Rocket: Don't.
Rocket: Fine! No Hell! No demons! This place isn't even haunted!
Rocket: Great. Joke's over. Hat, pull me out.
Mash: Busy.
Rocket: Doing what? You've stood there all day! You've got a hook the size of a bus! Just lower it!
Rocket: ...Do that again.
Rocket: You don't have footprints.
Host: Go back and look. His first shot. No shadow. Everybody's breath fogs but his. Snow has landed on every hat in this yard but one. You've been staring at it for nine minutes.
Rocket: You're a ghost?
Gravity: You didn't know?
Pressure: Everybody knew, tin can.
Host: In 2007, a commission decided to take the rig apart. So they did.
Rocket: I flew up here for a fake haunted hole, and it has a real ghost?
Mash: Boo.
Rocket: AAAAAAAAAAAH
Rocket: Why are you still here?
Mash: 12,262.
Host: Metres. 7.6 miles. Deeper than the deepest ocean. Mount Everest would fit, if it was 9 inches wide. Nobody has ever dug deeper. China's new well got to 10,900.
Mash: Hm.
Rocket: Your name says 15,000.
Mash: Yes. 9,000 feet short. I wait.
Rocket: At 30 feet a good day. That's 300 days.
Mash: If nothing breaks.
Rocket: So what stopped you? The heat? Him?
Mash: Invoice.
Host: The heat was brutal and the walls kept falling in. They still got back, by 1990. Then in December 1991 the country paying for the pipe ended. Deep drilling stopped the next year.
Pressure: I was winning!
Rocket: Big name for a guy who stopped at twelve.
Mash: You named yourself Rocket.
Mash: You are in a hole.
Rocket: Wait. You're a ghost. So who's pulling me out?
Mash: You have reverse?
Rocket: I have confidence.
Host: All those years got about 0.2 percent of the way to the center of the Earth. This is the hole, drawn to scale.
Rocket: Where?
Host: It's inside the black line around the Earth. We can't draw the line thin enough.
Host: This month Voyager 1 gets so far from home that light takes a full day to reach it. 16 billion miles. About 2 billion times farther up than this hole goes down.
Rocket: 2 billion to one! That's my side! That's me! Up is...
Mash: Up is empty.
Rocket: So nobody's been down there. So nobody knows what's down there.
Mash: Shh.
Host: But there is a real recording. No doctor. No microphone on a wire.
Host: You can tell what's in a barrel by knocking on it. A huge earthquake knocks on the whole planet, and the planet rings.
Host: This is real. Japan's great earthquake, 2011. A whole month of it, on a seismograph in an old silver mine in Germany. Sped up 400,000 times, with the quiet end turned up. We added nothing.
Host: That one steady note is the whole Earth swelling and shrinking, a tiny bit, once every 20 minutes. For weeks.
Rocket: Oh, that is awesome.
Host: Waves like those are mostly how we know what's inside. Nobody's ever been. People listen.
Mash: Sound said layer. We went to look.
Rocket: You were checking the tape.
Mash: Yes. All those years I growl. I was too loud to hear.
Rocket: Mash. Don't look at me.
Rocket: I have a reverse.
Mash: Since when?
Rocket: The factory.
Mash: You stayed in hole.
Rocket: I wanted to hear how it ended.
Gravity: Everybody comes back.
Rocket: There. In case anybody asks how deep you went.
Mash: It unscrews.
Rocket: I know. And I'll still beat you.
Mash: By lunch?
Rocket: ...Some lunch.
Host: 30 feet a good day. Three hundred days. And nothing left to break.
Mash: Kola.
Governor: So how are things in Hell?
Mash: Cold today.
Gravity: ...Awesome.
Host: Next Sunday. A woman in Denmark finds the middle of the Earth, with cards in oatmeal boxes.
Sources
- Drilling history of the Kola Superdeep Borehole: start in 1970, passing a US well's record, 12,066 m reached in 1983 and a pause for the 1984 Moscow congress, the 27 September 1984 break leaving the turbine and 5 km of pipe, the restart from 7,000 m, 12,262 m in 1990, turbine drilling, aluminum alloy pipe, the 214 mm bit, bit life of about 4 hours and 7 to 10 m, 21 hour round trips at 12,000 m, up to 60 m a month, 120 °C planned and 212 °C measured, no basalt layer, mineralized water, drilling stopped in 1992, mothballed in 1995, the 2007 decision to dismantle Uralmash 15000.Lobanov, Chicherov and Sharov, 2021
- An early look at the hole and its findings.Vidal, GeoJournal 1984
- The crew designed the plug themselves to stop vandals dropping things in, a brick for example; it unscrews so instruments can go down.Yevgeny Klimov interview, RT, 2021
- The lid on the hole today.Argumenty i Fakty, 2019
- Life at the rig.Respublika Bashkortostan, 2018
- The history of the project.RIA Novosti, 2020
- David Guberman, the project's chief, spent twenty years brushing off the Hell story, and a state governor greeted him with a question about Hell.Svobodnaya Pressa, 2011
- The Well to Hell legend checked.Snopes, The Well to Hell
- The recording surfaced years later through a radio show correspondent, via an uncle's friend at the BBC; it is a looped and processed recording of screams; Rendalen labeled a building inspector's photo as Dr. Azzacov; the story first appeared in 1989.Skeptoid, The Siberian Hell Sounds
- The trail from a Finnish Christian group's magazine to a letter in a Finnish daily, a newsletter and a California newsletter; Rendalen saw the telecast while visiting; he clipped a story about a building inspector and signed with his real name, address and phone number plus a pastor friend; the network ran it without contacting him; found in about 45 seconds through directory assistance; “None of it is true. I fabricated every word of it!”.Rich Buhler, TruthOrFiction
- Christianity Today reported the story as a hoax, with the teacher's admission, in its July 1990 issue.Christianity Today, 1990
- Project Mohole: drilling 600 feet into the sea floor off Mexico in 1961, the cost estimate climbing past 125 million dollars, and Congress ending it.Project Mohole, National Academy of Sciences
- The wine breakfast at Walter Munk's house where Mohole was pitched.National Academies Press, the wine breakfast
- President Kennedy's message on the success of the first phase of Project Mohole, April 1961.American Presidency Project, Kennedy's message
- The slogan: the ocean's bottom is at least as important as the moon's behind.Geochemistry, Geophysics, Geosystems (Mohole slogan)
- The 10 kopeck Soviet stamp of the Kola borehole, issued in 1987.Soviet stamp, 1987 (Wikimedia Commons)
- The deepest point in the sea, shallower than the hole is deep.Guinness World Records, deepest point in the sea
- China's Shenditake 1 reached 10,910 m, the deepest vertical well in Asia; completion announced in 2025.Drilling Contractor, 2025
- Voyager 1 reaches one light day from Earth, about 16 billion miles, in November 2026.Voyager 1, NASA
- The Earth's breathing mode has a period of 20.5 minutes and kept ringing for months after the 2004 Sumatra earthquake.Rosat, Watada and Sato, EGU 2006
- Seismic waves are how we learned what is inside the Earth.American Museum of Natural History, Inge Lehmann
- The Black Forest Observatory sits in a disused ore mine near Schiltach, under up to 170 m of rock, run by KIT and the University of Stuttgart.Black Forest Observatory, KIT
- The Black Forest Observatory is in the Anton mine, a former silver and cobalt mine near Schiltach.Westerhaus, Zürn and others, KIT (Black Forest Observatory)
- Seismic data for the 2011 Japan earthquake, station BFO: 33.6 days, breathing mode at 0.814 mHz.Global Seismograph Network, station BFO
