Call Florida's Port of Palm Beach a small waterfront with big plans.

Having opened a 100,000-square-foot cold-storage facility last year, port and city officials journeyed to the Costa Rican capital this week to meet with potential shippers attending the IV Business Forum of the Americas.''Traditionally, Costa Rica has been a container market. We're trying to bring in the concept of breakbulk and palletization in addition to the traditional containerization,'' said Louis Perez, Palm Beach's deputy port director.

''There is a different market out there than this part of the world is familiar with.''

Palm Beach is the busiest port for shipments of Florida sugar, which moves primarily in domestic carriage. It was the top Florida port trading with Cuba up until Fidel Castro's rise to power, and is preparing for an eventual resumption of trade ties. With Tropical Shipping as its flagship carrier - strong in Central America and the Caribbean - Palm Beach increasingly sees itself as an international player.

At transportation infrastructure seminars and in private discussions this week, Port of Palm Beach executives are trying to press for investment in cold-storage facilities in Costa Rica and elsewhere in Central America.

''What we're trying to convey is the concept that we have a cold-storage facility at our end of the transaction and we can accommodate their fruit once they make investments in the area of perishable cold storage,'' said Mr. Perez, whose port's main client is Tropical Shipping.

The Tampa Port Authority, increasingly interested in working with Crowley American Transport in promoting Americas trade, will be pressing the same theme this week at the San Jose forum, which precedes a meeting on Thursday and Friday of hemispheric trade ministers who must agree on a framework for a Free Trade Area of the Americas.

Florida's largest ports of Jacksonville, Port Everglades and Miami did not send representatives to the forum, but Palm Beach officials see themselves increasingly as an alternative to the more congested, larger East Coast waterfronts in the North-South trades.

''The Central American and South American marketplaces are clearly knocking at our doorstep,'' said Alfred Zucaro, a city commissioner in West Palm Beach. ''This is a continuation of the effort on our part to become more of a destination point for international commerce.''