WITH clouds above and choppy waves battering the boat, my diving trip in Kenya didn't seem to be starting on a good note. The boat jumped over the waves and thumped against the water; rain splattered the 25 wetsuit-wearing divers on board.

The captain navigated wildly - if effectively - through a "mlango," Kiswahili for "gate," a gap in the reef where boats exit the lagoon through deep water. Finally, we made it to calmer seas and the divers broke into applause.

My queasiness subsided as I remembered what brought me here: a barrier reef and tropical waters teeming with marine life - manta rays, turtles, dolphins and even the elusive whale shark - in one of the least-known but most spectacular dive sites in the world.

We were in Diani, a beach along the Kenyan coast about 322 miles east of Nairobi. We were heading to a wreck, an old fishing trawler, that the dive center sank in 2002. All the dive sites along Diani lie parallel to the coastline, part of a 125-mile-long barrier reef.

Diving takes place beyond the reef. It is an ideal location for beginners, since dangerous sharks are rare here. But the site also appeals to experienced divers, especially those craving a glimpse of the whale shark. At up to 10 tons, they are the largest-known fish; they allow divers who encounter them to get very close before they swim away, and they have never been known to attack humans.

As I descended into the waters off Diani, the water got murkier and chillier and the prow of the wreck came into view. Schools of tropical fish surrounded us. Swimming around the wreck, we saw barnacles and all kinds of fish, including rumpets, triggers, bats, guitars, soldiers, bigeyes, banners and a resident lion fish. Our time underwater flew by; after 40 minutes, we emerged.

The rainy weather had given way to bright sunshine. On the boat, the friendly dive guides and instructors offered us fresh fruit to re-energize. We relaxed and soaked up the sun for a little over an hour before gearing up for our second and last dive of the day.

We moved to a reef called Kisima Mungu. As we descended once more, we caught a glimpse of a three-legged green turtle as it swam away.

Next we encountered a friendly pilot fish, which looks a bit like a barracuda. It tried to bite our fins; for a moment, we worried that it was in fact a barracuda looking for prey. After a few minutes it departed.

Go: Paola Safaris, paolasafaris.com; for diving, Diving the Crab, from $90, divingthecrab.com.

-AP