Our fascination with the ocean's depths has certainly inspired innovative creations throughout history - by the 1300s, the Persians invented the world's first goggles, thinly sliced and polished tortoise shells that enabled them to see underwater, while in the 16th century, divers used barrels as diving bells to keep them momentarily submerged.

Today, apparatus is the least of our concerns; the keenest divers are looking for exclusive and unique experiences in the big blue sea. These special spots aren't always easy to access, but therein lies the appeal.

For many divers, the ultimate goal is to have a truly unique experience - exploring an undiscovered spot. The term is thrown around loosely by companies marketing to tourists, but experts say that it can be possible to dip your flipper into unexplored waters. So thinks Daniel Magnan, the diving instructor at North Island (Wilderness Safaris) in the Seychelles. "Lots of places in the ocean are undiscovered, especially here where we are in the Seychelles on the Mahé Plateau. On GPS, the contour lines are not 100 per cent accurate, and only boats cruising around the area will be able to find perfect spots for diving," he explains. Upon these discoveries, Magnan and his team will return and plot these areas for future adventures.

The average depth near North Island is 18 to 35 metres and slopes to greater depths. "There is often a strong current here, making diving exclusively for the brave," he says. But the extraordinary dive is worth every effort - hard corals, such as the fast-growing staghorn coral (acropora cervicornis), various sharks, large shoals of fish such as blue-banded snappers and kingfish, and round ribbontail rays are aplenty. "Everything is possible here, and you can have the best dive of your life," he says. Guests staying at the private island can then have an unforgettable one-off experience whereupon they are taken to a completely new dive spot, at the whim of Magnan and his boat.

History buffs or divers wishing to stick a little closer to home may favour the east coast of Sri Lanka instead - waters that have been closed off for decades due to civil war and a tsunami. As such, the coast holds largely unexplored diving sites that are now being viewed for the first time in a few centuries. Much of the diving here is centred around wrecks - the world-class diving wreck MV Cordiality is just 10 minutes from the town of Pulmudai by boat, and the 1922 British Sergeant, a marine oasis leaning on its side, is just a 30-minute boat ride from Kayankerni. For true adventurers, there are still locations off the coast of Batticaloa that are truly unexplored.

Novelty is clearly a key draw for divers looking for the next big thrill. The sport has enjoyed immense popularity for years, but today's adventurers are looking for more than just pretty coral and camera-friendly fish - they need moments to remember.

Iceland, for example, offers a unique underwater spot perfect for those looking for a once-in-a-lifetime experience. In the Thingvellir National Park, a Unesco World Heritage area, divers can swim between two of the earth's biggest continental plates. In addition to the otherworldly views, a large part of the appeal also comes from the fact that any shift in the tectonic plates could alter or perhaps even obliterate this diving gem forever. There is a price to pay for this special dive, however - the water here is frigid, and divers require thermal undersuits and full-body drysuits to withstand the extreme temperatures.

For many divers, these costs are worth it, as there is much to be said for the emotional aspect of the activity. Many divers nowadays require something more than just spectacular views with their dives - they want the opportunity to be part of a story.

"A quality diving experience cannot and should not be defined just by its cost or its location," says Tom Marchant, co-founder of the travel company Black Tomato. "Just because it is expensive or far away doesn't mean it's any good. We also look beyond just seeing the classic marine life. We look to explore shipwrecks that come with stories, get dug into natural phenomena, or diving ancient Indian ruins in Lake Titicaca or with Beluga whales as you look up at the iceberg towering over you in remote arctic Canada."

One of the most interesting diving sites, according to Uga Escapes - with a new resort Chena Huts near Yala in Sri Lanka - is the HMS Hermes. It is the world's first purpose-designed aircraft carrier, so exploring its depths not only challenges divers technically, but it also exposes them to its unique structure. The wreck is also home to a large variety of marine life - perhaps even more than a reef can offer - from large tuna to grouper and jacks all flocking around.

Accessibility has certainly improved in recent years given increased awareness and the push for sustainability. While these diving spots might not be the most exclusive, they often offer a treasure chest of variety and diversity. "The privilege of diving and the access to rare sites is only possible with an awareness of ecosystem health and the importance of protecting these unique environments," says One & Only Reethi Rah's resident marine biologist, Kylie Merritt. "The Maldives is an exclusive diving destination considering that local authorities decided to protect reefs in general - their corals, giant animals, clams, hump-head wrasse, turtles, all rays, reef sharks and whale sharks - more than 20 years ago."

There's something out there for every diver who wants to take their underwater experience to the next level. "In my view, a great diving experience is one that taps into our innate desire to explore," Marchant says. "It's a form of travel that can still generate the feeling of being a pioneer and knowing that you are experiencing something that few have on the planet; an increasingly hard thing to do today."

 

BUCKET LIST THE

FAMOUS ONE:

● The Great Blue Hole sinkhole (pictured below) is easily one of the top diving spots in the world. This brilliant dark-blue pupil is 305 metres across and surrounded by an iris of green, and it sits right in the middle of the Belize Barrier Reef. It is also clearly visible in the crystal-like waters just 70km off the shore of Belize. The visibility is so good that you can even see it from space.

HOW TO GET THERE: There are daily flights from many cities across North America. Book on American Airlines (aa.com).

OTHERS TO TRY:

● Turks and Caicos from the Amanyara (aman.com/resorts/amanyara)

NAME OF THE SITE: Hole In The Wall

HIGHLIGHT: A swim through which starts around 45 degrees, goes down vertically to about 90 degrees and then right angles and slopes out on the wall around 100 degrees. There is a large school of master snappers near the hole itself at the top of the wall around 40 degrees, and the scattered coral heads are populated with rare fish such as reef butterfly fish, viper moray eels, giant green moray eels, chestnut moray eels and spotted eels.

LOCATION: This is on the far south side of the wall, yielding a slightly barren look with low-lying rubble but accentuated by raised coral heads and pillar coral stands.

DEPTH: There is a minimum depth of 12.2 metres.

SKILL LEVEL: Intermediate to advanced

HOW TO GET THERE: Jet Blue, with now an ever-expansive network, has daily flights for most of the year from New York. It’s just over three hours to reach Providenciales. Book on jetblue.com.

 

The Philippines from the Amanpulo (aman.com/resorts/amanpulo)

NAME OF THE SITE: Jalah

HIGHLIGHT: The surrounding wall boasts many colourful corals and various types of fish. Another interesting sight here is the graveyard for ships’ anchors – fishing boats that have gone to this area to protect themselves from bad weather dropped their anchors but were never able to recover them.

LOCATION: On the eastern side of Manamoc, Jalah is only a 10- minute boat ride away from the resort.

DEPTH: There is a coral wall dropping from 12.2 metres down to 38.1 metres. The wall goes around 360 degrees, which gives the impression of diving into a volcano.

SKILL LEVEL: Intermediate to advanced

HOW TO GET THERE: From Hong Kong, a quick hop on Cathay Pacific takes you to Manila and from the private airport hangar of the Aman, the island is easily reached. Book on cathaypacific.com.