It wasn't exactly like being in the sunny Caribbean during last night's snowfall, but it may have been the next best thing.

The Hospital Relief Fund of the Caribbean sponsored a festive Caribbean Carnival complete with a Trinidad steel drum band banging out reggae sounds, floating rounds of rum punch and margaritas, and a five-course dinner with native island dishes.

A 2-year-old nonprofit organization, the Hospital Fund raised $30,000 through last night's event, to be dispersed to rundown hospitals throughout the Caribbean.

"We need the money very badly," said Commonwealth of Dominica Ambassador Frank Baron, speaking not only of the relief fund, but of the Reagan administration's expected proposal to allocate $300 million to the Caribbean Basin.

"The devastation by hurricanes David, Frederick and Helen caused in a 12-month period was frightening," said Baron. "It ruined homes and crops. Our economy is down to rock bottom. The banana crop, which is 70 percent of our economy, was wiped out twice. We desperately need the money for rehabiliation."

"The Caribbean is within the orbit of the U.S. and it would benefit all of us if we can stand on our feet alone," said Sir Keith Johnson, Jamaican ambassador.

Talk of the social and economic help the United States would provide many of the impoverished islands did not entirely overshadow the military and business advantages of such aid.

"Take one look at the geography on a map and it's easy to see that any aggressor would have a perfect spot to launch an attack against us," said Rep. Richard T. Schulze (R-Pa.), a strong proponent of the president's program, which would also protect some American business interests. "If you think the Soviets are close in Nicaragua, it would be a disaster for us if they moved into the Caribbean.

"If we don't help, someone else will, and there are always strings attached to what they do. They always extract a price." And our price? "If we do have a price, it's not nearly as high as theirs."