These are the craziest holes ever dug

Ever wanted to know more about the deepest boreholes ever dug? Maybe you want to know more about the challenges faced when drilling down at deep levels? Maybe you want to know why the deepest boreholes had to stop being drilled? Well read on, dear reader, and learn more about the 10 deepest boreholes ever dug and the teams that took on these challenges.


Located in the north of Chile is a massive copper mine, known as the Exotica Mine. It’s one of the largest open pit mines ever created, measuring just under 2.8 miles long and over two miles wide, reaching a depth of over 3000 feet deep.

The team who dug the mine encountered many challenges when digging to this depth, due to the localised boulders and cobbles found in the ground.


Found in the Okra Mountains outside Salt Lake City, the Bingham Mine extracts copper.

Since 1848, the mine has produced 20 million tonnes of copper, and is currently sitting at 2.5 miles wide and nearly 4000 deep – making it the deepest open cut mine in the world! However, mining has not yet wrapped up and the mine is expected to continue getting deeper for years to come.


Built at a cost of $279 million dollars and finished in 2010, the Icecube Neutrino Observation station was created to detect subatomic particles – called neutrinos.

In order to detect them the scientific team had to dig deep underground to remove background interference. This was done by blasting hot water into the ice using a 25,000-pound hose.

After three weeks of blasting, the team drilled the borehole to an impressive 8000 feet (2440 metre), depth into the ice.

#7 Geothermal engineering limited – England

In 2018 in Cornwall England, a geothermal company dug two holes to access the hot rocks and turn liquid water into steam, thereby powering turbines for energy production.  

The project team defied expectations and was able to complete the project in six months, with the crew claiming it had reached 17,000 feet (5180m), reaching temperatures up to 392 degrees Fahrenheit (200 C).

#6 CHIKYU – Japan

Chikyu is a Japanese drilling ship and is known for targeting regions with heavy seismic activity.

In 2012, it reached a drilling record of 25,000 feet (7620m) beneath the ocean floor. At the time, the ship was located off the Oscar peninsula in Japan, and managed to beat the record set by the Glomar Challenger in 1978 which dug down to 23,000 feet (7010m) in the Mariana Trench.

Offshore drilling brings about its own set of challenges. While this isn’t the deepest borehole ever drilled, it’s certainly impressive being able to get so far down when having to face the challenges brought on by keeping a ship in position in the middle of the ocean.

#5 KTB Borehole – Germany

Operating from 1987 and 1995, the KTB Borehole reached a depth of 29,000 feet (8839m). Getting to over 932 degrees Fahrenheit (500 C). Liquid and gases flooded the drill hole, creating dynamic rock, proving a surprise to the scientists who were expecting metamorphic rock.

#4 Bertha Rogers – Oklahoma

The Lone Star Producing Company 1–27 Bertha Rogers hole or well was an oil-exploratory hole drilled in Oklahoma in 1974, and was the world’s deepest hole until it was surpassed in 1979.

The drilling started October 25, 1972 and it took Lone Star a little over a year and a half to reach 31,441 feet (9,583 m) on April 13, 1974.

During drilling, the well encountered enormous pressure – almost 25,000 psi (172,369 kPa).

No hydrocarbons were found before drilling hit a molten sulfur deposit, which solidified around the drill string, causing the drill pipe to twist-off and a loss of the bottom-hole assembly. The well was plugged back and completed in the Granite Wash from 11,000 to 13,200 feet as a natural gas producer.

#3 Deepwater Horizon – Texas

Built for $560 million, BP leased the oil drilling platform to drill the wells.

Deepwater Horizon worked on wells in the Atlantis and Thunderhorse oil fields. It was described at times as a “lucky” and “celebrated” rig, and in 2007 was still described as “one of the most powerful rigs in the world”.

In 2006 it discovered oil in the Kaskida Oil Field, and in 2009 the “giant” Tiber Oil Field. The well in the Tiber field had a true vertical depth of 35,050 ft (10,683 m) and a measured depth of 35,055 ft (10,685 m), below 4,132 ft (1,259 m) of water. The well was the deepest oil well in the world, and more than 5,000 feet (1,500 m) farther below the seabed than the rig’s official drilling specification stated on the company’s fleet list.

In February 2010, Deepwater Horizon commenced drilling an exploratory well at the Macondo Prospect, about 41 miles (66 km) off the southeast coast of Louisiana, at a water depth of approximately 5,000 feet (1,500 m).

Deepwater Horizon was working on the Macondo site on 20 April 2010, when a violent explosion occurred leading to destruction of the rig and the subsequent oil spill. There were several contributing factors to the explosion, but the central cause was a faulty Blow Out Preventer. This oil spill has been recorded as the largest offshore spill to occur to date, resulting in 40 miles (64 km) of coastal pollution.

During its operational lifetime, the rig was actively in operation for 93% of its working life (2,896 of 3,131 days). The remainder partly was time spent moving between sites.

#2 Sakhalin-1 – Russia

Since 2003, when the first Sakhalin-1 well was drilled, six of the world’s 10 record-setting extended reach drilling wells have been drilled at the fields of the project, using the Yastreb rig, and has set multiple industry records for length, rate of penetration and directional drilling.

On 27 August 2012, Exxon Neftegas beat its previous record by completing Z-44 Chayvo well. This ERD well reached a measured total length of 40,604 feet (12,376 m), making it the longest well in the world

#1 Kola Superdeep Borehole – Russia

Sitting at number one is the Kola ‘Superdeep’ Borehole – one you are probably already aware of!

Referred to as the “Kola well,” it was drilled for research purposes beginning in 1970. After five years, the Kola well had reached about 23,000ft (7,000m). Work continued until the project was abandoned in 1989 because the drill became stuck in rock at a little over 8 miles (12km) deep. That is the current record for a depth reached by humans. The project cost over $100 million, which is about $2500 per foot. That is some expensive digging!

Given the technology and funds, geologists would like to try to go deeper for core samples, but digging such holes requires much patience, money, technology, and luck!