These four unpopulated islands (Negritos consists of two islands) in the Gulf of Nicoya were included in the national park system as biological reserves to protect seabird-nesting colonies and spare them from tourism or other development. The park service maintains no facilities for visitors on any of the islands, nor are there any trails to speak of.

Essentially steep-walled chunks of rock jutting above the ocean's surface, these islands support low, scrubby, dry forest vegetation. The thin soil and limited annual rainfall combine to produce harsh conditions for plant growth. However, the western Negritos island once had someone living on it, as is surmised from the remains of a wooden house and various introduced fruit trees. Pre-Columbian pottery fragments found on the same island indicate that it may have been used as a burial site by the previous inhabitants of the Nicoya Peninsula.

To get there: The easiest way to see the Guayabo and Negritos islands is to take one of the daily cruises from Puntarenas to Tortuga Island, since the route taken on these excursions passes by these islands. Likewise, the ferry from Puntarenas to Paquera also passes near Guayabo Island.

The only other alternative for closer examination of these island biological reserves would be to hire a small boat to take you out to them. This could possibly be done in the village of Paquera, or to visit Isla Pájaros, in the village of Costa de Pájaros located 21 kilometers off the PanAmerican Highway, north of Puntarenas.

Climate: Hot and sunny most days of the year. The small amount of rain that does affect these islands falls between May and November.