The Four Seasons Explorer is a three-deck catamaran that sails around the Maldives. The island chain is still struggling to rebuild and recover its tourism industry after the tsunami that hit the area in December 2004.

It’s not simple getting around the Maldives - 1,200 islands make for complicated transit. I took the only high-end cruise around a portion of the islands, aboard the smallest Four Seasons in the world and the only one that floats.

The Four Seasons Explorer is a handsome, three-story motorized catamaran that offers half-week or full-week cruises to inhabited islands and some of the Maldives’ great diving and snorkeling sites.

Other ships also ply the Maldives, primarily dive-site ships, because the nation has some of the world’s great diving. The Four Seasons offers a snorkeling and a diving itinerary each day - often twice a day - plus visits to several islands to check out what life on a desert island in the middle of the Indian Ocean is like.

The ship, decorated in teak woods and subdued colors, has been operating since 2002. Business is not what it was in the Maldives before the tsunami in December - it’s off by about half. Plus this is the slow season, so when I was aboard a few weeks ago, the 11 guest staterooms, enormous by cruise ship standards, were not fully occupied; I was one among seven guests, supported by 25 crew.

A typical day aboard the Explorer begins with a buffet breakfast and choice of a hot, kitchen-cooked meal and ends in a spacious living room with a look at the day’s underwater events, photographed and edited into shape by the ship’s videographer, plus a rundown of the next day’s travel by the easygoing cruise director, Tom Northway.

In between come diving, snorkeling, sunset fishing, optional water sports and classic Four Seasons meals - some dinners on tiny, uninhabited island beaches if the weather holds - often featuring local fish among the choices. The table service, led by a crewman named Arief Faisal, was impeccable, always accompanied by scented, chilled wet facecloths that are a trademark of the Maldivian resort dining ritual.

The divers were impressed daily by the displays of manta rays and other animals and by the crew’s underwater leadership. I was with the snorkelers, led by the ship’ marine biologist, Guy Stevens, who also gives a daily sea-life talk on board. He pointed out much as we snorkeled, and by the end of the week I could identify many of the prominent undersea residents, from the magnificent powder-blue surgeonfish that is the Maldives’ national fish, to the clownfish that imitates Nemo.

One day, I snorkeled for a while just above a huge sea turtle that glided alongside a coral reef. On another, I was in a raft with crew members, suddenly accompanied by perhaps 60 spinner dolphins that jumped from the sea and twirled like figure skaters in a competition. They were feet from the boat.

The ship sails from island to island - never at night. The last depth surveys of the Maldives were taken in 1835 and provide the maps pilots use to navigate the nation. Waters shift, islands change shapes, coral reefs change depth. Once, says constantly vigilant Explorer captain Boni Sebayang, who comes from Indonesia, he found an island 300 meters away from its place on the nautical chart. That’s not unusual, he says with a knowing smile. ‘‘I come to what’s supposed to be an island - and it’s not there. Or I find a reef that was not supposed to be there.’’

The ship rates change seasonally; summer rates were about $1,700 per person for three nights, double occupancy.