A wave is being blamed for overturning a boat and dumping seven persons aboard into the Gulf of Nicoya about noon Thursday.
The Cuerpo de Bomberos de Costa Rica said the boat was owned by Reyner Sandoval, a firefighter. Those aboard also were off-duty firemen.
The mishap took place about 80 meters off the Isla San Lucia, and four persons were able to swim to shore, the agency said. All wore life jackets.
One person in the water suffered some form of nervous attack, said the Cuerpo de Bomberos, so two other persons stayed there until a rescue boat arrived.
Responding were the Servicio Nacional de Guardacostas and CR-02 a vessel of the Cuerpo de Bomberos, the fire agency said.