Once you become an expert diver, there are times when you long to take a break from sightseeing dives, and spend some time at more challenging sites. There's no doubt about it - from the deep alpine lakes of Europe, to sheer walls off the Virgin Islands, to massive shipwrecks in deep, out of the way places, this planet's waters hold plenty of challenges even seasoned technical divers find thrilling. You'll find that not all these extreme dives are super deep or even terribly challenging; instead, our list of favorites includes some different "extremes" - in terms of temperature, locale, and other conditions. We hope you enjoy these unusual sites as much as we do.
The Crater, Utah
An extreme dive, at a resort? That's right! The Crater is located at the Homestead Resort and Spa, just outside Midway, Utah. This is the largest and deepest hot spring in the United States - and that's not all, it's tucked inside a natural cave and accessed via a 100 foot long limestone tunnel which was blasted into the mountainside to make it simple for visitors to get to the hot springs. A relatively new dive site, the Crater was opened to the public in 1996. The water is a balmy 95 degrees Fahrenheit, and a natural hole in the dome overhead allows fresh air and sunlight to penetrate the mountain. The crystal blue water offers a maximum depth of 65 feet, and a number of on-site amenities, including diver training, are available.
Nemo 33, Belgium
Located in Brussels, Belgium, Nemo 33 is the world's second deepest diving pool. Built specifically for divers, and opened in 2004, this site is one of the most popular in the world - it hosts about 25,000 divers annually. A unique setting that features a number of training platforms and a man-made abyss, Nemo 33 offers filtered, un-cholorinated spring water that is maintained at 86 degrees Fahrenheit, which is just about 10 degrees warmer than some of the world's nicest tropical dive sites. Maximum depth here is 34.5 meters, and there are a number of underwater caves (man-made, of course) which enable visitors to hone their skills.
Underwater photo shoots and movie shoots happen here, and so do underwater weddings. There's a restaurant with views into the pool, plus there are shops, a bar, and more; there is even a swimming area for non-divers to enjoy. While we love natural dive sites, this 2.5 million liter pool is a fantastic indoor diving paradise you've got to see at least once!
Eagle’s Nest Sinkhole, Florida
Often considered to be the Grand Canyon or Mount Everest of cave diving, Florida's Eagle's Nest Sinkhole is also known as Lost Sink, and is by far one of the most challenging dive sites in the world. Located near Weeki Wachee, within the Chassahowitzka Wildlife Management Area, the sinkhole is far from impressive at first sight! On the surface, it appears to be nothing more than a fairly scummy pond; once below the surface, you'll find crystal-clear water, huge caverns about the size of a high school gymnasium, and an even bigger main chamber called the Main Ballroom, from which a number of tunnels extend into the distance. While there is a permanent line installed in the main chamber, the side tunnels are very dark and it is in these tunnels that most fatal mistakes are made. Maximum depth at Eagle's Nest is 300 feet, and more than a few divers, including experienced cave divers, have lost their lives here. Infrastructure is minimal, and help is far away. Use extreme caution, but enjoy this cave if you're qualified and experienced enough to dive it. In a word, Eagle's Nest is astonishing.
McMurdo Sound, Antarctica
Thanks to advances in technology, and to improved travel infrastructure, diving in Antarctica is getting to be quite popular. It's extreme in every sense of the word, though - temperatures can be below zero, and the ice can be as much as ten feet deep. McMurdo Sound offers exceptional visibility of up to 300 meters, and is home to a wealth of marine life. Brilliant yellow cactus sponges and vibrant green sea globes, incredible red jellyfish, sea urchins, and huge sea spiders can be found here, along with huge sea worms, fish specially adapted to life in frigid water that would kill most other fish species, and Antarctic penguins in search of squid and other prey are just some of the creatures you'll share your dive with if you're brave enough to take the plunge.
Dive trips to Antarctica require plenty of advance planning, and take place during the Southern Hemisphere's summer months. You'll hear the songs of whales as they pass in the distance, and the odds are good that you'll see them from your boat. If you don't mind the cold and you want to take some of the most extreme dives in the world, all on one trip, then this is one to add to your bucket list.
Samaesan Hole, Thailand
The deepest dive site available in the Gulf of Thailand, Samaesan Hole is 85 meters deep and is for technical divers on Trimix only. This site isn't just extreme for its depth; it is known for its strong currents and for its visibility, which is often quite poor, due to silt. It's also extreme for what's on the bottom - tons of unexploded ordinance! Samaesan Hole was used and an explosives dumping ground and is marked as such on navigational charts. In addition, it is located in the middle of a busy shipping lane; gas and oil tankers pass through daily, with their hulls cutting deep into the water - right into the space you'll be conducting safety stops.
Divers have been swept away and picked up by passing fishing vessels here; it's best to do this dive at slack tide. If you want to kick your adrenaline into high gear, this site will do the trick.
We can't stress the importance of safety enough. Be sure to follow all recommendations for safe diving, and never exceed the boundaries of your training or experience. By taking all possible precautions, you'll be able to conquer the world's most exciting dive sites with confidence - and enjoy the process, while you're at it.