Exploring the Great Blue Hole of Belize - The Ultimate Guide

The Ultimate Guide To The Great Blue Hole of Belize

The Great Blue Hole

Belize is home to many natural wonders, from the world’s second-largest barrier reef to miles of dense jungle teeming with life. None are perhaps more impressive and awe-inspiring than the Great Blue Hole that adorns Belize’s coastal waters. This unique geological formation has captured the imaginations of people for centuries. Aside from its aesthetic value, the Blue Hole nurtures a teeming ecology and has a fascinating history. Read on to learn more about this landmark that draws people from around the world to come to see it for themselves.

What Is It?

The Great Blue Hole is a naturally-occurring marine sinkhole located about 62 miles off the coast of Belize City, near the center of Lighthouse Reef. It is considered part of the larger Barrier Reef Reserve System, which is a UNESCO World Heritage Site. It has also been declared a natural monument within Belize itself – one of the country’s seven wonders.

The hole appears as an almost perfect circle and is the largest natural formation of its kind in the world. It is about 984 feet across and 410 feet deep. The depth of the water gives it the deep blue color from whence it takes its name. Whether you dive into it, simply see it from the surface or have the opportunity to view it from the air, the Great Blue Hole of Belize makes for a striking and beautiful sight. It is even visible from space and easy to spot in the Belize Barrier Reef formation due to its distinct shape.

A Geologic History

Belize’s marine formations are somewhat unique in that they are the only true coral atolls in the Western hemisphere, although Chinchorro Reef, off Mexico’s Yucatán Peninsula and just north of Belize’s formations, is sometimes considered to be one as well. Geologists have confirmed that the way Belize’s coral atolls formed doesn’t resemble that of the better-known atolls in the Pacific Ocean, adding to their unique nature.

Belize’s atolls likely began developing around 70 million years ago. Unlike the coral atolls found in the Pacific Ocean, they did not develop around volcanoes and instead did so on top of large fault blocks. These limestone-covered ridges settled in stair-like formations, which provided a perfect offshore environment for coral growth.

The Great Blue Hole itself was originally a cave that formed when sea levels were much lower. Over time, water weathered away at the limestone, shaping it in the same way caves across the planet are formed. This created the visibly striking stalactites and stalagmites visible at the site today. These have been analyzed and were found to have been formed at various periods across tens of thousands of years: 153,000, 66,000, 60,000, and 15,000 years ago.

As the last ice age ended, the sea rose slowly, which caused the coral to grow upward into the formations seen today. The caves were flooded and submerged, turning an above-ground cave system into a marine wonder. The drop-offs along Belize’s atolls are sometimes thousands of feet deep, while the shallow lagoons that form on the inside are only about ten to thirty feet deep. This is typical and to be expected based on how scientists know these formations were created.

Recent History

Archeological evidence which remains shows that ancient Mayas inhabited some of Belize’s atolls for over a thousand years. Any names they might have had for the Great Blue Hole or any features of the surrounding area are unknown.

The atolls and the Great Blue Hole were first recorded by Europeans between 1528 and 1532 when the Spanish charted the shoreline and offshore areas along Central America. Any names these Spanish explorers gave to islands, atolls, and landmarks in the region, including the Great Blue Hole, have also been lost to history.

The names for the modern sites in the area all stem from English discovery when Britain occupied Belize beginning in the 1750s. Lighthouse Reef used to be called Eastern Reef or Quattro Cayas, but was renamed when a lighthouse was built on Half Moon Caye in 1820. Once called Longorif, Glover’s Reef now bears the name of English pirate John Glover, who used the spot as a hideout. Turneffe Atoll seems to have originally been named Terre Nef.

The Great Blue Hole itself was named by British author and diver Ned Middleton. He mentioned in his 1988 book “Ten Years Underwater” that if Australia could have a famous natural landmark called the Great Barrier Reef, then Belize should have its Great Blue Hole. The name stuck and has been in use ever since.

Charles Darwin, commonly known as the father of evolutionary theory, saw Belize’s atoll formations for himself and was rather impressed. He called the Belize Barrier Reef, Belize’s atolls, and the Great Blue Hole, “…the richest and most remarkable coral reefs in the entire western Caribbean.” Coming from one of the most respected and groundbreaking naturalists in history, this is high praise indeed.

The famous marine conservationist Jacques Cousteau brought worldwide attention to the site when he featured it on his television show, “The Undersea World of Jacques Cousteau.” He declared it as one of the top five sites to SCUBA dive in the world. His expeditions in the 1970s confirmed the Blue Hole’s geological origins as a cave system that had originally formed above sea level before being flooded. Prior to this, the site had mostly only been known by scientists and local Belizean fishermen.

In 1997, an expedition by the Cambrian Foundation was conducted to record details about the cave system and retrieve core samples from the seafloor at the bottom of the Blue Hole. This expedition was noteworthy because it was a truly multi-disciplinary effort where the best techniques of science and diving were used together.

Another research expedition was conducted in 2018 to create an accurate map of the Great Blue Hole’s interior using sonar scanning. This revealed a previously-unknown layer of hydrogen sulfide. The bodies of two missing divers were also discovered at the bottom, a stark reminder to practice all safety precautions and rules when diving in the Blue Hole.


The Great Blue Hole provides a rich habitat for a wide variety of marine species. Among the coral formations live tropical fish such as groupers, squirrelfish, angelfish, butterflyfish, and midnight parrotfish. Several species of reef sharks, including nurse sharks, the Caribbean reef shark, and the Blacktip shark, inhabit the Blue Hole as well. Pederson’s cleaning shrimp and neon gobies can be seen everywhere among the anemones and coral heads. The Blue Hole is surrounded by the reef and around the rim sponges, sea fans, sea turtles, barracudas and other species that call the reef home can be seen. For visitors who can’t or don’t want to dive fully into the Blue Hole, snorkeling in the surrounding waters offers a much easier experience.

Other shark species, such as hammerheads and bull sharks, have been reported around the Blue Hole but are not commonly seen there. The possibility of catching a sight of these rarer creatures entices and excites many people who want to SCUBA in the Great Blue Hole.

Firsthand Accounts

Divers report that although the Great Blue Hole is very deep, the astonishing clarity of the water allows divers to get a clear view of its marine wildlife, interconnected ecosystem, and cave formations. The dive is especially suited to people who love cave diving. Divers go down to a maximum of about 130 feet.

Divers have remarked that the experience of diving into the Great Blue Hole can be otherworldly, especially on days with good visibility and the wildlife is more active. “Gothic,” “quiet,” and “eerie” are all terms that have been used to describe the experience. Because of the depth, the dive is short, however, which occasionally does not meet divers’ expectations. A dive tour at the Great Blue Hole is usually accompanied by dives in other areas of Lighthouse Reef to give a complete picture of the area’s ecosystem and natural formations.

It should come as no surprise that the Great Blue Hole is consistently ranked as one of the best diving spots on Earth and even among the most amazing places in general. In 2012, Discovery Channel placed Belize’s Great Blue Hole at the number one spot on its list of the 10 Most Amazing Places on Earth.

Visiting Yourself

Day trips to the Great Blue Hole are available from the resorts and coastal tourism towns of Belize. While most dives are done as day trips, there are options for overnight dive trips to Lighthouse Reef as well. Divers from all over the world jump at the chance to dive at such a unique location, and it is common for both divers and snorkelers to explore the shallowest depths of the Blue Hole. This is not a dive for beginning divers, as it is complex and requires a level of responsibility and experience that many new drivers do not possess. You must have completed a minimum of 24 dives before you will be allowed to dive at the Great Blue Hole.

Due to the Great Blue Hole’s depth, the bottom is so deep that there is no light or life. Researchers have even found dead conchs and hermit crabs that had fallen to the bottom of the Blue Hole and suffocated. Never venture down farther than what is safe, and heed the instructions of your diving guides. Ascend when they tell you to and do so at a manageable rate. Do nothing to stress other divers and avoid diving with anyone who may cause you stress or whom you do not trust. Following standard diving safety procedures will help ensure a safe, enjoyable experience for everyone.


The Second Blue Hole

Belize actually has another blue hole that is lesser-known but no less phenomenal. Unlike the Great Blue Hole, this one is located inland near the center of the country, about twelve miles south of Belmopan. This hole is found within the St. Herman’s Cave System and is part of a national park. Locally it is known simply as the Blue Hole. Similar to its bigger cousin, the Blue Hole is a sinkhole that formed when an underground river channel collapsed. You can even see an exposed section of the Cave’s Branch River tributary before it disappears underground again.

It is easy to access the Blue Hole via a short flight of stairs from a parking area. You can go for a swim in this hole, and it is actually an ideal spot for a cool, relaxing soak. This can feel especially good after hiking the trails through the surrounding rainforest and exploring the nearby cave system.

Belize is known for its natural wonders big and small, but the Great Blue Hole is certainly one of its biggest. There is nothing else quite like it in the world and it is not to be missed if you will be visiting the country.

Get a copy of The Ultimate Belize Bucket List! Written by Larry Waight, a local with more than twenty years of experience in the travel industry, the book is packed with tips, information, and recommendations about all of the best things to see and do in Belize.
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