Underwater cave diving is exciting and thrilling, but like other adventures, sticking to caves that match one’s skill level is important. While one must always step out of one’s comfort zone to improve, there is nothing shameful in staying away from these riskiest underwater caves around the world if one is an amateur diver.
Scuba diving in all its forms requires proper training, certification, and experience (and there are many dive certifications to get before reaching pro-level). Even for the most advanced and experienced divers, going beyond one’s certified level (and skill level) is absolutely ill-advised. However, even those with the right training and certs find themselves avoiding risky caves underwater, and these are some prime examples of such spots.
10 Diepolder Cave System, Florida
A view of turquoise-colored waterbody
Florida is not all about white sand beaches and vibrant theme parks (like Disney and Universal Studios). It also has some of the world’s most dangerous underwater cave diving sites, one of which is the Diepolder Cave System. Located in the Sand Hill Ranch Scout Reservation, this spring system is made up of two separate caves – Diepolder II (360 feet) and Diepoder III (300 feet). With a depth of 360 feet, Dipolder II is considered the deepest cave in the continental US.
Both caves are beautiful, but due to their depths, divers who wish to explore the cave system are required to show proof of at least 100 cave dives through the Abe Davis of the Wakulla Award. Divers are also required to be fully trained in cave diving by either the National Association for Cave Diving (NACD) or the National Speleological Society Cave Diving Section (NSS-CDS).
9 The Shaft, Mount Gambier, Australia
A diver at the entrance of an underwater cave
The Shaft is like nothing most divers have ever seen before. This underwater cave is more than 120 meters deep, and what makes it even more fascinating is that it can only be accessed via an opening in a grass-covered field. Inside the underwater caves, it is overwhelmingly dark, and the tunnels are so many that divers can easily get lost, and getting lost in such a cave is somehow synonymous with drowning. In 1973, four divers tragically lost their lives in this cave after they became lost and then drowned, and that just proves how dangerous it can get in this cave.
8 Kisby Sinkhole, Mount Gambier, Australia
A diver at a cave entrance
The shaft is not the only sinkhole in the Mount Gambier area. Kisby Sinkhole is also located there, and it is also one of the most exciting dive sites in the world. The sinkhole is 60 meters deep, and its waters are some of the clearest in the world. The clear waters and the piercing rays of daylight make diving here enjoyable. However, it is worth knowing that up to six amateur divers have died in this sinkhole since 1969. Perhaps they were trying to explore some of the caves, which are better left for experienced divers due to their extreme depths.
7 Eagle’s Nest Sinkhole, Florida
Divers in an underwater cave
Florida has many of the world’s best underwater caves, some of which turn out to also be some of the riskiest. Eagle’s Nest Sinkhole is just one of these caves. This underwater cave is hundreds of feet deep and is filled with several narrow passageways that can be difficult to go through. It is also totally dark within the caves, which makes it even more difficult. Up to 10 people have lost their lives trying to explore this cave since 1981. Some of these victims were even experienced divers, which just makes this site an absolute “no” for beginners.
6 Temple of Doom (Cenote Calavera), Mexico
Cenote Cavalera, also called the Temple of Doom, Tulum, Mexico
The Temple of Doom is not for the faint-hearted. Divers who are brave enough to explore this cave are first required to walk 200 feet to the entrance and then jump from eight feet into the 50 feet-deep sinkhole. Inside, divers will be met with the beautiful effects of the rays of sunlight and several stunning rock formations. Divers will also be met with a canyon system that features many tunnels, which can be dangerous for amateur divers.
5 Jacob’s Well, Texas, United States
Jacob’s Well, a popular local swimming hole near Austin
Jacob’s Well in Texas is considered one of the most dangerous dives in the world due to its extreme depth and the complexity of the cave system. The well reaches a depth of 120 feet, and it takes experienced divers about five hours to dive to the deepest part of the cave system as divers will have to deal with narrow passages that can trap and lead to drowning. Up to nine people have died in these caves, but the cool temperature of the waters and the beautiful underwater scenery has continued to attract divers from all over the world, especially in summer.
4 Silfra Fissure, Iceland
A scuba diver at Silfra fissure, Iceland
Although not a cave-like others on the list, Silfra Fissure is just so unique that it is worth mentioning on any dangerous underwater cave list. The risk that awaits at Silfra Fissure is not dangerously dark and narrow holes and others that one would expect; instead, it is the freezing temperature of the water that makes it risky. With the waters at a temperature of two degrees Celsius, it feels risky to even touch the water, not to talk of actually diving in it.
The rewards of this dive, however, make up for all the risk one has to put up with. The Silfra Fissure is the only place on Earth where one can touch two continents at the same time while snorkeling or diving, and the waters are often considered the clearest in the world.
3 The Submerged Cosquer Cave, France
Calanque of la Triperie, near Cape Morgiou in Marseille, France. In the Calanques massif is the Cosquer underwater cave
The submerged Cosquer Cave is one place that should interest lovers of archeology and prehistoric art as much as underwater cave divers. It is the only known underwater cave from the Stone Age, which just makes it fascinating. Within the cave are hundreds of paintings of animals and humans that were made between 27,000 and 19,000 years ago. This is the kind of cave that all adventures have to check out at least once. It is, however, not so easy to explore this cave. About three divers got lost and died while trying to explore this cave. The entrance is about 37 meters underwater, and it leads into a tunnel that goes upward into the half-submerged cave where the paintings can be seen.
Unfortunately, the Cosquer Cave is not open to the public because it has been made a protected historic monument. However, a replica exhibition of the cave has opened in the Villa Mediterranee in Marseille that allows people to see the cave without actually going underwater. To book this tour, visit the Cosquer Cave booking website.
2 Blue Hole, Dahab, Egypt
Free divers at the famous Dahab Blue Hole in the Red Sea in Egypt
The Blue Hole in Dahab is one of the best dive sites in the world. However, it has one of the highest records of diving fatalities in the world. In just 15 years, more than 150 divers have lost their lives exploring this 120 meters-deep submarine sinkhole in the Gulf of Aqaba in Egypt. This has made many to now refer to the hole as the diver’s cemetery. Many of the divers were even experienced, like Yuri Lipski, whose death has been named one of the most chilling diving deaths in history. One would ask why this hole is so popular despite being associated with many deaths. This is because, besides its abundance of sea creatures, this hole is also filled with stunning sea walls and several caves and tunnels, some of which lead to the open sea.
1 Pluragrotta Cave, Norway
A lake in Mo i Rana, in Rana municipality where the Pluragrotta Cave is located, Norway
The Pluragrotta Cave is extremely dangerous even for the most experienced cave divers in the world, yet it remains one of the most popular dives in Scandinavia. As the deepest cave in Northern Europe, there are many challenges associated with this cave. Besides the freezing temperature of the water, the cave extends to a dangerous depth of 135 meters and has dark and narrow sections made up of sharp edges that can damage dry suits and disorient divers.
Pluragrotta Cave has been dived since the 1980s, but 2014 brought a lot of controversy to the site. On February 6, 2014, two divers died in the cave, and the extreme depth made rescue impossible for the international team invited to recover the bodies. Diving was therefore banned in the cave, and the bodies were abandoned.
Despite the ban, friends of the deceased (who had also participated in the first dive that led to the deaths) went back into the cave and successfully recovered the bodies. That act of heroism by these wonderful friends – Patrik Gronqvist, Sami Paakkarinen, Kai Kankanen, and Vesa Rantanen – led to the lifting of the ban by the Norwegian authorities on March 31, 2014. This inspiring rescue mission has even been made into an interesting documentary titled – Diving into the Unknown. The BBC also made an amazing story of the rescue mission. Today, the cave can still be explored but only experienced divers with a lot of bravery, skill, and expertise should ever attempt this.