The latest resort in the Maldives archipelago opened this month on a secluded sliver of sand known as Vagaru Island. Here, 61 thatched villas stand along a pristine shore, lapped by the cerulean waters of the Indian Ocean. All have private decks and plunge pools, with airy, whitewashed interiors. There are four restaurants, a spa and a Padi-certified dive centre which leads to coral reefs and exotic aquatic life, and offers boat trips out to neighbouring atolls.
Viceroy, Vagaru Island, Shaviyani Atoll, Maldives (00 960 654 5000; viceroyhotelsandresorts.com). Doubles from US$1,350 (£900), B&B. Diving from US$110 (£73).
This exclusive resort on Hamilton Island is surrounded on all sides by the largest contiguous coral reef in the world: the Great Barrier Reef. Here, guests can spend days exploring the 2,000km-long spectacle by boat, helicopter or seaplane, with two-tank dives or simple snorkelling gear opening up a world of tropical colour.
Later, relax in the resort's sumptuous spa; dine on fresh fish at the seafood restaurant; then slumber in one of 60 modern pavilions or beach houses, which each have a private pool and deck.
Qualia, 20 Whitsunday Boulevard, Hamilton Island, Queensland, Australia (00 61 2 9433 3349; qualia.com.au). Doubles start at A$975 (£635), including breakfast. Diving from A$115 (£74).
Frégate Island, Seychelles
A tiny drop of granite rock, tropical foliage and crystalline sand in the Indian Ocean is home to this blow-the-budget private island resort. Here, the lofty prices open up a world of abundant birdlife overhead and a host of mystical-sounding dive sights in the emerald waters below. Guests can plunge to Monument Valley, spend time scouring Grande Anse Reef or brave the shadowy depths of Barracuda Rock. More sedentary pursuits include sunset cruises, dining in one of four gourmet restaurants, unwinding in the Rock Spa or relaxing in your secluded private villa.
Frégate Island, Seychelles (00 248 4 670 100; fregate.com). Villas from €2,700, full board. Diving from SCR2,600 (£117).
Amanyara, Turks & Caicos
This Amanresort is set within a marine park on Providenciales island. From its dive centre, it has unfettered access to pristine reefs teeming with tropical fish, turtles and stingrays. Above ground, open-air pavilions channel the cool breeze of the Atlantic through refined interiors.
Amanyara, Providenciales, Turks & Caicos (001 649 941 8133; amanresorts.com). Doubles from US$1,573 (£1,048). Diving from US$450 (£300).
The Oberoi, Egypt
For proximity and diversity, the Red Sea is hard to beat. Here, the Oberoi at Sahl Hasheesh has its own house reef, explorable through snorkelling, scuba diving and night dives. After a day under the Egyptian sun, repair to a warren of cool white buildings, crafted to resemble the architecture of the region with domed roofs and pillared entrances.
The Oberoi, 117 Sahl Hasheesh, Red Sea, Egypt (00 20 65 3440 777; oberoihotels.com). Doubles from €268, room only. Diving from E£475 (£50).
Turtle Inn, Belize
This 25-room seafront hideaway is owned by Francis Ford Coppola. It offers year-round tank dives around the cays and bays of Belize's Caribbean coast or seasonal night excursions to see whale sharks from April to June. Other activities include canoe trips to inland lagoons and tours of the Cockscomb nature reserve, home to 80 protected jaguars.
Turtle Inn, Placencia Village, Stann Creek, Belize (00 501 523 3244; coppolaresorts.com). Doubles from US$285 (£190), B&B. Diving from US$145 (£97).