SAN JUAN, Puerto Rico — The turquoise waters and white-sand beaches of the Caribbean appear to be losing some of their allure for U.S. tourists.

Americans who flocked to the islands in record numbers until recently are finding new destinations or staying home, leading to declines of more than 10 percent this year on such islands as Jamaica, St. Lucia and Grenada.

Governments have aimed marketing pitches at Canada and Europe to compensate for slippage in the U.S. market, which has been accounting for about 60 percent of the region's vital tourism business.

"The trickle-down effect is huge," said Richard Kahn, a spokesman for the Caribbean Tourism Organization. "In the long run, this could mean the loss of jobs throughout the Caribbean."

A new passport rule has discouraged some travelers. Americans returning by air from the Caribbean have been required to present a passport since earlier this year, although the U.S. is temporarily also accepting proof of passport application because of a backlog.

But even U.S. territories unaffected by the new security measure have seen declines — the number of Americans visiting Puerto Rico dropped 9 percent in January compared with the same month last year, and the U.S. Virgin Islands saw a 7 percent drop.

Some simply want more exotic destinations.

"A lot of the larger islands are reaching that point where their market has been there, done that and is looking for a different experience," said Cheryl Carter, a tourism instructor at Florida International University.

Ken Zapanta, a 30-year-old Californian, said he and his wife enjoyed their visit to Barbados two years ago but won't follow up with another Caribbean trip.

"Once was enough," he said. "The beaches, you can get that anywhere."

The number of American visitors dipped in the months after the 9/11 attacks before surging more than 10 percent over four years. Last year, U.S. tourists staying overnight reached a peak of 11.5 million, according to statistics from the Barbados-based CTO.

Terrorism worries boosted the Caribbean's appeal as a safe, nearby destination, said Joe Goldblatt, a lecturer at Temple University's School of Tourism and Hospitality Management. Over time, more U.S. tourists began visiting distant continents.

Facing uncertainty over when trends might reverse, Caribbean officials are focusing promotional efforts elsewhere.

Jamaica, hit by a 12 percent drop in U.S. visitors this year, has started advertising more in Canada and Europe, said Basil Smith, Jamaica's tourism director. A strong euro helped boost European visits by 22 percent through April, he said.

The "spice island" of Grenada arranged for the German airline Condor to offer weekly service year-round instead of only in the winter, said tourism board spokesman Edwin Frank. St. Lucia is negotiating with British Airways and Virgin Atlantic Airways to provide more flights.

Some analysts predict U.S. tourism will rebound quickly; they attribute the recent decline in part to a sluggish U.S. housing market that has cut into Americans' spending.

But others fear the new passport requirement will haunt Caribbean resorts for years.

"Once an American has now got a passport, the world is their market," said Alec Sanguinetti, chief executive of the Caribbean Hotel Association. "They can go anywhere."