The vast Indian Ocean contains around twenty percent of the world's water and is home to idyllic islands that are blessed with luxurious hotels and fringed by world-class dive sites. If you're looking for the best diving in the Indian Ocean, then your choice is between two of the ocean's stunning archipelagos. The African archipelago of the Seychelles consists of 115 rugged islands and is located northeast of Madagascar, while the Maldivian archipelago, consisting of 1,192 pristine coral islands, is considered a part of Asia and is situated to the southwest of Sri Lanka. While they both provide stunning diving, their topside characters are subtly different: the picture-perfect Maldives conjure images of serene white-sand islets topped by tropical palms, featuring some of the world's most luxurious resorts, while the more rugged Seychelles, bathed in lush vegetation and superb walking trails, is also no stranger to providing ocean-side luxury.

Seychelles beach

The Seychelles

While it may be the smallest of all the African nations, the Seychelles pack a mighty punch when it comes to marine life. The remote islands sit around 800 miles east of the African mainland and are spread out in clusters across the cobalt-blue ocean. If you're on a mission to uncover the best diving in the Indian Ocean, an island-hopping itinerary through the archipelago will allow you to compare and contrast the best diving destinations that the Seychelles has to offer: Desroches & Alphonse, The Aldabra Group, Cosmoledo and Astove.

Desroches & Alphonse

The two luxurious private islands of Desroches and Alphonse sit within the Amirantes group of coral islands. Île Desroches, or Desroches Island, is located about twenty miles east of the Amirantes Bank and is separated from it by a 1,300-metre-deep channel. The entire island takes up less than two square miles and is encircled by a golden-sand beach, which is especially attractive to nesting green and hawksbill turtles.

Alphonse Island is a short 30-minute hop by light aircraft to the south. The Alphonse Group consists of two stunning atolls that are only around a mile apart and separated by a deep channel. Alphonse Atoll in the north features the group's only inhabited island, Alphonse Island, while St. François Atoll in the south is composed of two uninhabited islands, St. François and Bijoutier.

The diving around the Amirantes island group is incredible: sharks, macro critters, colourful reef fish and plenty of silvery pelagics - dogtooth tuna, wahoo, dorado and sailfish - are all commonly encountered on the healthy reefs. Keep one eye on the blue too, as you never know who will show up to surprise you on the remote dive sites, with whale sharks and thresher sharks occasionally stopping by to wow divers.

thresher shark

The Aldabra Group

The Aldabra Group is composed of two islands and two atolls, which sit 200 miles north-west of the northern tip of Madagascar. The atolls and islands - Aldabra Atoll, Assumption Island, Cosmoledo Atoll and Astove Island - are some of the Seychelles most remote, and their dive sites serve up some of the best diving in the Indian Ocean. Clouds of colourful reef fish flit to and fro, never straying too far from the comfort of the reef's nooks and crannies, and predatory wahoo, jacks and tuna swoop by on the hunt.

Keep your fingers and toes crossed for a passing hammerhead or thresher shark, and you may even be lucky enough to have your surface interval interrupted by breaching humpbacks or a thousand-strong pod of melon-headed whales. The Aldabra Group dive sites are some of the most remote in the world, and remote diving usually translates into huge numbers of fish, great visibility, and the occasional surprise passing by in the blue, and that's exactly what to expect when you back-roll off the boat here.

The Maldives

Sitting a little over 1,200 miles north-east of the Seychelles are the low-lying coral islands of the Maldives. No conversation regarding the best diving in the Indian Ocean can pass without the Maldives getting a mention. Famed among seasoned divers as a hotspot for manta rays and whale sharks, the island chain runs from Ihavandhippolhu Atoll in the north to Addu Atoll in the south, crossing the Equator along the way. While the diving throughout the Maldives is spectacular, you can (over)simplify your planning by deciding what you wish to see: head north for mantas, hit the central atolls for whale sharks, and the southern atolls for hammerheads and tigers.

Manta in the water

Northern Atolls

The atolls of Baa, Raa, Lhaviyani and Noonu are found towards the northern tip of the Maldivian island chain and, among other highlights, feature the world's premier manta ray aggregation site, Hanifaru Bay, in Baa Atoll. The atoll was declared a Biosphere Reserve by UNESCO in 2011, and there is a strict code of practice in place to protect the mantas.

Each year, hundreds of manta rays congregate in the bay to gorge themselves on plankton. Hanifaru Bay's natural shape funnels the plankton into a small area, and the mantas barrel-roll through the bay with their mouths agape. But it's not all about the mantas up north; keep an eye out for whale sharks trying to grab their share of the plankton too, while octopus, nudibranchs and frogfish can all be found on the reef. There's even the chance of seeing a rare white-spotted guitarfish in the deep!

Central Atolls

While the northern atolls may be the best place to see manta rays in large numbers, you will have a great chance of seeing these graceful rays throughout the country's dive sites, including the stunning central atolls, nearer to Male. But if you prefer 'big and spotty' to 'big and flappy' and have a hankering for watching whale sharks hoover up plankton, then the more central locations of South Ari Atoll and North Male Atoll should be on your radar.

In addition to plenty of whale sharks and a few manta rays, you can also expect pristine house reefs, which are perfect for a relaxing late afternoon dive. Scan the reef's nooks and crannies for ghostpipefish, myriad nudibranchs, octopus and leaf scorpionfish. But lift your head up now and again; there may be a turtle or reef shark cruising by.

black-tipped reef shark

Southern Atolls

The shark-filled waters surrounding the Maldives' more southerly atolls can certainly offer some of the best diving in the Indian Ocean for serious shark enthusiasts. Hammerheads, tigers, grey reefs, white- and black-tipped reef sharks and occasional thresher sharks all hang out in the Maldives' deep south. While it's often touted as the best shark diving in the Maldives, there's so much else to see too; Fuvahmulah Atoll is also visited by giant oceanic mantas and sailfish, while there's always the chance of a whale shark sighting too.

The southern atolls are becoming ever more accessible too. While a few years ago the only real option was liveaboard diving, fans of house reefs and macro lovers can also enjoy the pristine house reefs of the recently opened resorts on the southern atolls. As impressive as the house reefs are in the Maldivian south, with porcupine rays and marble rays keeping the macro critters company, it's the sheer variety of shark species on display that ensures the southern sites are among the best diving in the Indian Ocean.