The Mystery Of Belize's Blue Hole: What Lies Beneath?

Belize's Blue Hole is a giant marine sinkhole off the coast of Belize. It is located near the centre of Lighthouse Reef, about 70 km from the mainland and Belize City. The hole is circular, measuring 318 metres across and 124 metres deep, and formed during several phases of the Quaternary glaciation when sea levels were much lower. In December 2018, an expedition team including Richard Branson, Fabien Cousteau, and Erika Bergman descended to the bottom of the Blue Hole in a submarine. They discovered a layer of hydrogen sulfide at a depth of about 300 feet, below which the water becomes anoxic and devoid of life. They also found the bodies of two divers, hundreds of conches, and various human rubbish, including plastic bottles.

A toxic layer of hydrogen sulfide

The Great Blue Hole, a giant marine sinkhole off the coast of Belize, hides a toxic layer of hydrogen sulfide at a depth of approximately 300 feet (91 metres). This layer, formed naturally over centuries, shrouds the depths in darkness and strips the water of oxygen.

Hydrogen sulfide (H2S) is a colourless, flammable, corrosive, and toxic gas. While it is less concentrated in the Blue Hole in its dissolved state, it is still potent enough to prevent sea life from passing through. The gas forms a thick chemical layer that blocks out all light from above, creating an eerie and lifeless environment below.

The hydrogen sulfide layer acts as a barrier, preserving anything that falls below it. Erika Bergman, a National Geographic Explorer and submersible pilot who led an expedition into the Blue Hole, explained that anything that falls into the hole decomposes, using up all the oxygen below the H2S layer. This decomposition process results in a complete lack of oxygen at greater depths, leaving a graveyard of fallen creatures.

The toxic layer also contributed to the tragic deaths of divers who ventured into the Blue Hole. The absence of oxygen at depths below 290 feet means that any divers who pass through the hydrogen sulfide layer will quickly run out of breathable air. The bodies of lost divers discovered at the bottom of the Blue Hole serve as a stark reminder of the deadly nature of this underwater environment.

The discovery of the hydrogen sulfide layer and its impact on the ecosystem within the Great Blue Hole highlights the importance of understanding and protecting this unique natural wonder.

Crabs, conches and other creatures

The Great Blue Hole in Belize is the world's biggest ocean sinkhole, measuring 300 metres (984 feet) across and around 125 metres (410 feet) deep. In 2018, an expedition team including Richard Branson, Fabien Cousteau, and Erika Bergman ventured to the bottom of the Blue Hole.

At a depth of around 300 feet, the team encountered a thick layer of toxic hydrogen sulfide, which plunged them into darkness and cut off the oxygen in the water. Below this layer, they found crabs, conches, and other creatures that had fallen into the hole and died due to the lack of oxygen.

Erika Bergman, the chief submarine pilot on the expedition, described the phenomenon as "conch graveyards," where conches accidentally fall into the hole and, unable to crawl back up, eventually suffocate. The sand quickly covers up the fallen conches, and the visible shells indicate a healthy conch population above.

The Blue Hole, with its depths and anoxic environment, serves as a stark reminder of the dangers posed by climate change and the impact of human activities, such as the presence of plastic bottles found at the bottom.

Human remains

The Great Blue Hole in Belize is a fascinating natural wonder that has long captivated the interest of explorers, scientists, and divers alike. With its vast depth and mysterious allure, it beckons to those seeking adventure and knowledge. However, the Blue Hole also holds secrets that are both intriguing and somber, including the discovery of human remains.

In December 2018, an expedition funded by billionaire Richard Branson and led by Aquatica Submarines ventured into the depths of the Blue Hole. The team included National Geographic Explorer and submersible pilot Erika Bergman, as well as Fabien Cousteau, the grandson of renowned underwater explorer Jacques Cousteau. Their mission was to create a 3D map of the Blue Hole's interior, but they ended up making a disturbing discovery.

As the team descended into the abyss, they encountered a thick layer of toxic hydrogen sulfide at around 300 feet (91 meters) below the surface. This layer acted as a barrier, plunging the depths into darkness and depleting the water of oxygen. It was below this layer, in the oxygen-deprived zone, that the team made a grim finding: the remains of two divers who had been lost in the Blue Hole.

The discovery of the divers' resting place brought a sense of solemnity to the expedition. Out of respect, the team decided to leave the remains undisturbed, notifying the Belizean authorities of their findings. Bergman described the site as "dark and peaceful," and the decision was made to let the divers rest there, their final resting place in the depths of this ancient sinkhole.

The presence of human remains at the bottom of the Blue Hole serves as a stark reminder of the dangers that lurk within this natural wonder. It also underscores the importance of approaching such expeditions with caution and respect for the unpredictable nature of the Blue Hole. While the discovery of the divers' remains was unexpected, it added a layer of complexity to our understanding of this enigmatic place.

The story of the Great Blue Hole is not just about its geological wonders and biodiversity but also about the human connection to this place. The discovery of the divers' remains is a reminder that even in the most remote and unexplored places, we encounter traces of humanity's presence and our impact on the natural world.

Plastic pollution

The Great Blue Hole, located off the coast of Belize, is the world's biggest ocean sinkhole. It is a popular diving site, made famous by Jacques Cousteau in 1971, who declared it one of the top five scuba diving sites globally.

In December 2018, an expedition led by Richard Branson, Fabien Cousteau, and Erika Bergman became the first to conduct a submersible dive to the bottom of the Blue Hole. The goal was to explore the underwater cave system and create a 3D map of the interior.

Unfortunately, in addition to the remains of two divers who had been lost in the hole, the team discovered plastic pollution in the form of plastic bottles. This finding emphasizes the extent of the world's plastic problem and serves as a stark reminder of the dangers of climate change and the urgent need to eliminate single-use plastics.

The Great Blue Hole is a unique and fragile ecosystem that has been impacted by human activity. The discovery of plastic pollution in its depths underscores the far-reaching consequences of our actions and the importance of conservation efforts to protect our planet's oceans and marine life.

As Branson noted, "The real monsters facing the ocean are climate change and plastic." It is crucial that we address the issue of plastic pollution and work towards sustainable solutions to protect our environment for future generations.

Ancient stalactites

The Great Blue Hole in Belize is a giant marine sinkhole that formed thousands of years ago as a limestone cave. It is located off the coast of Belize, near the centre of Lighthouse Reef, about 70 km from the mainland and Belize City. The sinkhole is circular, measuring around 300 metres across and 124-125 metres deep.

In December 2018, an expedition led by Richard Branson, Fabien Cousteau, and Erika Bergman ventured to the bottom of the Blue Hole in a submarine. They discovered a wall of giant stalactites, which Branson described as "breathtakingly beautiful". These stalactites are ancient, having formed when the cave was above sea level.

Analysis of the stalactites retrieved from the Blue Hole has provided valuable insights into its formation history. The cave went through several phases of formation during the Quaternary glaciation when sea levels were lower. Stalactites found in the Blue Hole have been dated to 153,000, 66,000, 60,000, and 15,000 years ago. As sea levels rose, the cave eventually flooded, submerging it and creating the Blue Hole we see today.

The stalactites found in the Blue Hole are enormous, with some exceeding 40 feet in length and two feet in diameter. Their existence and orientation provide evidence of past geological shifts and the movement of tectonic plates. Some of the stalactites are off-vertical by 5˚, indicating that the underlying plateau experienced tilting before stabilising in its current plane.

The discovery of these ancient stalactites has added to our understanding of the Blue Hole's formation and the geological processes that shaped the region. It serves as a reminder of the dynamic nature of our planet and the impact of climate change over time.

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