The Mystery Of Belize Blue Hole's Depths

The Great Blue Hole is a giant marine sinkhole off the coast of Belize. It is one of the country's top attractions and a popular diving site. In 2018, an expedition funded by billionaire Richard Branson and led by Erika Bergman, a National Geographic Explorer and submersible pilot for Aquatica Submarines, set out to explore the Blue Hole and create a 3D map of its interior. The team discovered a layer of hydrogen sulfide at a depth of around 300 feet, below which there is no oxygen and no life. They also found the bodies of two divers who had previously gone missing, as well as various trash items such as a Coke bottle and a GoPro camera. The Blue Hole is believed to have formed during the last Ice Age when sea levels rose and flooded a large limestone cave, and it serves as a stark reminder of the dangers of climate change.

A layer of hydrogen sulfide

The Great Blue Hole, a giant marine sinkhole off the coast of Belize, contains a layer of hydrogen sulfide at a depth of around 90 to 300 feet. This layer is toxic, corrosive, and has a strong odour. It is thick enough to block out all light from above, shrouding everything beneath it in darkness.

Hydrogen sulfide (H2S) is usually a colourless, flammable, corrosive, and toxic gas. In the Great Blue Hole, it is dissolved in water, creating a layer that blankets the entire hole. While it is less concentrated in this form, it is still potent enough to prevent sea life from passing through.

The hydrogen sulfide layer is situated at a depth where the oxygen in the Blue Hole has been entirely depleted. This means that anything that falls into the hole below this layer will be preserved, as there is no oxygen to facilitate decomposition.

The layer also marks the point at which life begins to disappear in the Blue Hole. Sea creatures that venture beneath this depth will perish, as seen in the graveyard of shellfish and conch shells found just below the H2S layer.

The hydrogen sulfide layer is not only a fascinating feature of the Great Blue Hole but also a critical indicator of the conditions within it. It serves as a boundary, separating the living world above from the dark, lifeless depths below.

No life

The Great Blue Hole, a giant marine sinkhole off the coast of Belize, is a place where no life exists at the bottom. At around 90 metres deep, a thick layer of toxic hydrogen sulfide spans the width of the sinkhole, blocking oxygen from getting any deeper. This means that anything that falls past this point will suffocate.

Erika Bergman, a National Geographic Explorer and submersible pilot for Aquatica Submarines, described how "conchs and conch shells and hermit crabs that had fallen into the hole and suffocated". She further explained that "without oxygen, nothing survives".

The hydrogen sulfide layer was formed when the Blue Hole was a dry cave. As sea levels rose, the cave flooded and collapsed, creating the Blue Hole as we know it today. This rise in sea levels occurred around 14,000 years ago at the end of the last Ice Age.

The Blue Hole is not only devoid of life at its bottom but also serves as a resting place for two divers who were lost in its depths. Their bodies were discovered by the Aquatica Submarines crew but left undisturbed out of respect.

The Blue Hole is slowly being filled by waterfalls of sand that tumble into it every day, and it may not be around forever. This natural wonder, though lifeless at its depths, continues to attract divers from around the world who are drawn to its unique geological formations and mysterious allure.

Conchs and shells

The Great Blue Hole in Belize is a massive underwater sinkhole that extends 124-125 metres into the Earth's crust. In 2018, an expedition funded by billionaire Richard Branson and led by National Geographic Explorer Erika Bergman of Aquatica Submarines, ventured to the bottom of the Blue Hole to create a 3D map of its interior.

The team discovered a series of mysterious underwater holes and a thick layer of toxic hydrogen sulfide that stretched across the sinkhole, preventing oxygen from going deeper.

Beneath the toxic layer, the team found conchs and conch shells, along with hermit crabs, that had fallen into the hole and suffocated due to the lack of oxygen. Bergman described this area as a "conch graveyard". The conchs and shells were found at a depth of around 90 metres, along with stalactites that indicated the hole was once a dry cave.

The discovery of the conchs and shells, along with other human trash and the remains of lost divers, highlighted the impact of human activity on this pristine natural environment.

Human remains

The Great Blue Hole, a giant marine sinkhole off the coast of Belize, has been explored by divers and scientists for years. With a depth of over 400 feet, it is the world's biggest ocean sinkhole. In 2018, an expedition team funded by billionaire Richard Branson and led by Aquatica Submarines set out to map the interior of the Blue Hole.

The team discovered a layer of hydrogen sulfide at a depth of 290-300 feet, below which there is no oxygen. This layer, though less concentrated than in its gas form, is still potent enough to prevent sea life from passing through.

In addition to marine life that had fallen and decomposed in the hole, the team also discovered human remains. The bodies of two divers who had been lost in the hole were found at a depth of 355 feet. The divers were believed to be two of the three people who had previously gone missing while diving in the Blue Hole. The bodies were left undisturbed, with the team deciding to notify the local authorities and leave the divers buried at sea, undisturbed and at peace.

The discovery of human remains in the Great Blue Hole serves as a reminder of the dangers of exploring such environments and the respect and care that must be afforded to those who lose their lives in the pursuit of knowledge and adventure.

Stalactites

The Great Blue Hole, a giant marine sinkhole off the coast of Belize, is home to millennia worth of stalactites and stalagmites. These formations are a result of the slow drip of water and the subsequent crystallisation of minerals as the water drops dry on the tip of the stone. As stalactites can only form due to water dripping down from above, their presence in the Great Blue Hole confirms that it was once a large, dry cave.

Analysis of stalactites found in the Great Blue Hole reveals that they formed in several phases, with the cave flooding as ocean levels rose. The stalactites indicate that the cave was above sea level 153,000, 66,000, 60,000, and 15,000 years ago. Some of the stalactites are off-vertical by 5˚, suggesting that there was also a past geological shift and tilting of the underlying plateau. This movement of the land, caused by the power of moving tectonic plates, is further evidenced by the enormous size of the stalactites, some of which are over 40 feet long and two feet in diameter.

The Great Blue Hole is a popular diving site, made famous by Jacques Cousteau in 1971 when he declared it one of the top five scuba diving sites in the world. The site offers divers the opportunity to explore the ancient past of the cave and view the impressive stalactites and stalagmites.

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