Tropical attitudes, turquoise waters, and a bounty of scenic islands make the Caribbean in general one of the world's most popular cruise destinations--and the Western Caribbean, in particular, beckons the adventuresome. It's a diving and snorkeling paradise, not to mention an archaeological treasure trove as well. The wonders of one of the world's great civilizations, the Mayan, lie near almost every port. And it's hard to think of another part of the world where cruise ship passengers are greeted with more enthusiasm. "What took you so long to come home, mon?" is the standard greeting in Jamaica, whether you're a first-time visitor or frequent traveler.