Under a hazy blue-pink sky out of a Monet painting, the West German registered cruise ship Caribe barely squeezed into the port of Alexandria yesterday, its 17-foot draft floating a mere three feet above the mud of the Potomac River channel. Murky water lapped at the gleaming white hull, and the sun appeared to perch just a foot above the flying bridge near the stern of the ship.

It was only 9 a.m. but the soon-to-be passengers of this ship were already on their way to the Ramada Inn a mile up river for their first ship's party: The bon voyage party, of course.

It might not have been as ausipicious an occasion as the sailings of the 1930s, when ships carried a nation's image and the departure of a Queen could draw 500,000 spectators to dockside.

But it was as grand a sea-going goodbye as has been seen in these parts in quite a while, since the 440 passengers, many of them local Virginia residents, were to board the first cruise ship ever to leave the port of Alexandria.

At prices ranging from about $600 to $1,000 a passenger, this sold-out 14-day ride will travel the 145 miles down the Potomac River to the mouth of the Chesapeake Bay, and then on to Haiti, San Juan in Puerto Rico, and St. Thomas in the Virgin Islands.

Ah, Romance.Ah, convenience.

Alexandria resident Maye Stewart 70, has cruised to Rio de Janeiro and traveled by bus through Mexico. She and 71-year-old Norman Eliston, who is paying her way as he always does when he takes her on their vacations, said they chose this cruise because "it leaves from Alexandria. We were going to go to New York and leave from there for San Juan."

William and Virginia McDonald of Arlington simply parked their car at the Ramada and then took specially provided buses to the ship, instead of taking an airplane to New York or Miami the two ports most cruise ships leave.

In the Ramada, people stood in clumps of families, some with corsages, others with Instamatics taking pictures. Children wished their parents and grandparents bon voyage.

Ellie Thurber, from Silver Spring, stood surrounded by her mother, father, aunt and other relatives going on the cruise with her."They're staying in another cabin," she said sweetly. Thurber's aunt convinced her to go on this cruise.

"Finally I said, well I'll just eat beans the rest of the year," Ellie Thurber recalled. "I'll spend my wad now. It'll be a fantastic getaway from the rat race. The children keep saying it's going to be like 'Love Boat,'" she said with a grin.

Thurber is leaving her husband behind. "It's not his bag. It would be too scheduled, too formal for him," she said. "Backpacking is his thing'" Her husband John studiously took pictures of the group as they assemebled at the Ramada.

Alexandria city councilman Bob Calhoun voted against the 440-passenger Caribe being brought into the Alexandria port when it was first suggested to city officials as a way to rejuvenate the waterfront. Neighbors had worried about the noise, Calhoun said. But he voted for it on another vote, he recalled yesterday morning, as he stood in the red velvet cushioned bar of the Caribe, sipping Cordon Rouge champagne at still another party. This one was a pre-departure party for city officials.

"Everybody in town said it was unsafe," recalled Alexandria Mayor Frank Mann grimly. "I've been reading all these grand and glorious stories about the cruise ship coming. Well, we really had to work to convince people this could work. We have a waterfront. We ought to use it for waterfront activities. We've had one of the tall ships. It just makes sense. It's a happy convenient place."

The cruise of The Caribe will be nothing like the 25-cent "horseboat" ferry ride that made a regular course from Georgetown to Alexandria in 1815, typical of the boat traffic that passed Alexandria in the 1980s. At the bon voyage party at the Ramada Inn, the passengers seemed to know the historical importance of this cruise ride. "In 1978 we did two important things," said Dennis Gallagher, the curator of the Friendship Fire Engine Museum, about Alexandria. "We got a professional baseball team, and we got a cruise."

Shortly before 1 in the afternoon, passengers assembled on the decks and grinned down at those remaining on the dock. Soon the endless rounds of eating and drinking would begin, most likely in the bar where newly arrived passengers have a penchant for ordering pina coladas, sometimes six rounds of them, according to one bar-tender.

A passenger at the rail of the ship called out a bet on the Redskins game to a friend below the ship's horn sounded a hoarse blast, a drum rolled, and the ship slowly moved out toward the Woodrow Wilson bridge.

"Have a good time," someone on the dock yelled up wistfully.