Just Gotta Dive's Favorite Danger Dives: From The Temple Of Doom To The Black Hole

Once you've spent season after season basking in warm water and enjoying idyllic, beautiful sites, you might join the ranks of some of our experts at Just Gotta Dive (JGD) in seeking dangerous adventure dives that will not only give you a thrilling adrenaline rush, but which will take you into some of the earth's most incredible hidden chambers.   Superb cave, wreck, and technical dive sites are of course available all around the planet, but some sites really do merit special mention.  Here are just five of our favorite danger dives. 

Great Blue Hole at Lighthouse Reef, Belize

One of the most amazing geologic features our planet has to offer, the Great Blue Hole is part of Belize's Lighthouse Reef System, and is located about 60 miles away from Belize City.  This perfectly circular hole is just under half a kilometer across; inside, the water is 145 meters deep.  This limestone sinkhole is surrounded by splendid coral reef, and up top, snorkelers and less experienced divers can take a peek down into the still, blue water below. 

Formed millions of years ago, when a a major earthquake caused the cave's ceiling to collapse and tilted the surrounding reef to an angle of about 12 degrees, the walls of this former dry cavern are peppered with ledges and overhangs, where you'll find stalactites, stalagmites, and even complete columns dating back to the Pleistocene era.  Tunnels and caves extend from the sides of the Blue Hole, leading into what is essentially an underwater mountain.  These are dark and deep; on the west side, there is a narrow entrance at a depth of 70 meters which leads into a large cavern.   In a far corner, a second tunnel leads upward into another cavern at a depth of 30 meters, where you'll find skeletal remains of sea turtles who died after being trapped inside the labyrinth.  It's pitch black inside, and visibility can be further compromised if the fine layer of silt is stirred up.  Keep in mind that several divers have lost their lives here, and do not enter the caves unless you are capable of adhering to cave diving rules.  Surfacing and decompression are two additional concerns this rewarding yet scary dive site brings to the fore; it's one you'll never forget.

Cenote Esqueleto Temple of Doom in Tulum, Mexico

Variously known to the diving community as the Skeleton Cenote and the Cenote Temple of Doom, this incredible cave dive is connected to Sistema Sac Aktun and is best accessed via Coba Road, off Tulum's Highway 307.  Signs pointing to this site identify it as Cenote Calavera, and there are several other cave systems in the same vicinity.  If you're heading west on Coba Road, this is the first cenote you will come to.  The water's surface is located about 10 feet from the sinkhole's lip, and is accessed via a leap off the edge into the water.   Before you jump in, be sure the ladder that leads up and out of the hole is in good working order, or you'll be stuck.  Once inside, you'll find yourself atop a circular heap of rubble - this breakdown pile was formed when the cenote's roof collapsed.  From here, a line leads to a cavern tour that circumscribes the pile's base.  From the line, you can enter one of two cave entrances downstream; either the Canyons, or the Madonna Passage.  Both lead to the Coliseum Room, then move toward the Hall of Giants.  Along the way, you'll see huge stalactites and stalagmites, and if you like, you can explore offshoot tunnels.  

Maximum depth inside the Temple of Doom is about 60 feet, with much of the cave being shallower.  Local dive centers have maps for sale, and plans are being made to create infrastructure - including stairs and restrooms - to improve the overall experience.  

Diepolder II Cave in Hernando County, Florida

This incredible cave diving destination is located on the Sand Hill Ranch Boy Scout Reservation near Brooksville, FL, and is the oldest working guide program anywhere, courtesy of the FSR (Florida Speleological Researchers.)   As this cave system is inherently dangerous, there are a number of regulations in place.  

• All divers must be fully cave trained, either through NSS-CDS or NACD - no exceptions.  In addition, all divers must be members in good standing of FSR.  If you're not a member of FSR, you can either join in advance, or join on the day of the dive.  

• Proof of 100 cave dives must be presented - either logbook entries or the Abe Davis Award or Wakulla Award are accepted. 

In addition, those wishing to dive Diepolder II must have a minimum of 3 dives logged at Diepolder III.    

While the main spring entry is unimpressive looking at just about 100 feet wide, and while the water at the entry appears cloudy, water inside the main shaft is crystal clear - some divers report having been able to see all the way down to the point where the line enters the cave system at 190 feet.   O2 is to be staged at 30 feet, and Nitrox is normally staged at 150 feet.    At 190 feet, the line splits - either way, you can make a circuitous route.  Rocks the size of tour busses litter the floor, and maximum depth at the back of the room is 230 feet.  The entire circuit is 500 feet around.  Average bottom time is about 20 minutes, and including deco, total dive time is normally about an hour and a quarter.

Blue Hole in Dahab, Egypt

Dahab's Blue Hole is over 200 meters deep, and is nestled along the shore side of a sheer wall that drops away to more than 800 meters.  It's connected to shore and to the open sea via a tunnel called The Bells, which is at a depth of 30 meters, and which gets its name from the noise divers' tanks make as they bump along the rocks.  The entire area is washed with currents, and it is vital that you carefully monitor air consumption and plan your dive with equal care. 

The blue hole itself is just about 25 meters across.  Inside, a formation called "The Arch" rises up from about 120 meters to crest at a depth of about 56 meters; both the Blue Hole Abyss and the Arch are out of reach for recreational divers, and a number of experienced divers have lost their lives inside - some of their bodies have never been recovered.   Whether you choose to dive deep inside the hole, which is fairly devoid of life, or if you decide to dive deep along the outer wall, where the coral and marine life are fantastic, this is one site which offers many opportunities for adventure. 

Black Hole in Andros, Bahamas

Located about 100 kilometers from Nassau, the Andros Black Hole is one of many; unlike some nearby black and blue holes, dives may only be undertaken for research purposes.  You will need to get advance permission to dive here, and it's vital that you be aware of the many risks this impressive karst formation holds.  Layers of carbonate mud extend from shore toward the center of the Black Hole, and inside, an oxygen-depleted layer of hot, dark pink to purple bacterial jelly separates the warm, brackish surface water from a crystal clear bottom layer.   These phototrophic sulphur bacteria require both sulphur and light to survive. 

The Black Hole is almost perfectly round, and is about 270 meters in diameter.  Measured maximum depth is 47 meters, with the southern portion of the lake featuring a sudden drop off, and the northern portion featuring a gradual slope to shore.  The upper water layer extends to a depth of 17.7 meters; you'll find some fish living here.  The bacterial layer is about a meter thick; the heat it exudes is created by chemical reactions inside the bacteria's cells, where extra light energy is transformed to heat.  The bottom layer is a cooler and is saline; it is devoid of oxygen and salinity is 35%.  The floor of the hole is coated in thick orange and purple microbial mats; some scientists speculate that this layer is representative of some of the first life on earth, when neither water nor the atmosphere contained oxygen.

Keep in mind, you'll have to go through the jelly layer not just once, but twice.  The lake will turn all metal black; even silver will tarnish instantly inside.  The bacterial layer and the layer below is toxic and hot.  Divers must access the site via helicopter, as wading and boat access are impossible.  This is a site most of us will never get to dive - and it's one most of us have decided to exclude from our bucket lists; if, however, microbiology is your specialty, this is a site you may decide to attempt. 

With the exception of Diepolder II and the Black Hole, all of these sites have something in common; that is, there is little to prevent divers without sufficient experience from attempting to go beyond the boundaries of experience and training.  Needless to say, we care deeply about your safety and recommend that you plan and execute all your dives carefully - especially these, which are the most dangerous the planet has to offer.