The prow of the old tuna boat sticks out of the water like a breaching whale. As I put on my scuba gear for the first dive of the day, the rusty jagged metal is a reminder of how dangerous these seductive blue and green waters can be. My guide, Asim Mohamed, jumps first, signalling that there is a current and we must drift on to the wreck rather than try to descend directly on to it.
We sink slowly through the pale water, startling a large female hawksbill turtle feeding on the reef slope. The current takes us over the wreck in seconds, and now, instead of rust and decay, there is brightness, colour and life. The old tuna boat is 30m long, her stern wedged into the sand like an abandoned toy. Underwater, the metal is transformed: after a quarter of a century of submersion, it has been covered with marine life, red and purple sponges, fat white tunicates and bulbous clumps of hard red and yellow coral.
On the sand, I shine my torch under the wreck and find two stingrays resting in the gloom. Their skirts ripple gently as they shy away from the light, and I leave them in peace. Ascending slowly around the hulk, Asim and I peer at the tiny creatures making their home on this artificial reef. Clouds of glassfish hide in the interior of the wreck, blending into the shadows. On the tilted deck, a goldbar wrasse darts behind a gorgonian sea fan, and I swim through a wall of surgeon fish that look as if they have been painted from a child's imagination: bright blue bodies, black faces and fluorescent yellow dorsal fins.
I am diving on the northern rim of Lhaviyani Atoll in the Maldives, an hour's fast boat ride from Four Seasons Landaa Giraavaru Resort, where I am staying. On the way back to the resort, we pass a handful of tiny islands ringed by satin sand, and a group of sleek-sided spinner dolphins dance around our bow wave, joyously leaping and twisting in the air. After a few days at Landaa Giraavaru, it's the kind of spectacle I have almost come to expect as part of the experience.
Beachside villas with private plunge pools are shaded from the Maldivian sun by casuarina pines and densely landscaped vegetation. The resort offers the customary five-star accessories, such as the infinity pool, the rooms on stilts above the lagoon, the indoor and outdoor showers, and staff who are so attentive that a pot of Ceylon tea appears at my breakfast table almost the instant I sit down. There's also a spa specialising in Ayurvedic treatments, and the opportunity to be pummelled and oiled and scrubbed with herbs — a process I discover to be uniquely relaxing. But I have come here to see the fish. And Landaa Giraavaru is doing its best to keep them happy, too.
In the shallow waters on the south side of the island, reef-scientist Thomas Le Berre takes me on a snorkelling tour of the reef. As with the rest of the Indian Ocean, the Maldives suffered badly from coral damage following a severe El Niño (climate phenomenon) event in 1998. Although many reefs in the Maldives are still healthy, others remain a pale shadow of their former glory. In that year, exceptionally warm water led the corals to bleach and die, a process that marine biologists link to climate change and that has affected many of the world's most important reef systems.
