In this marine park the most widespread type of vegetation is the mangrove, in which the red mangrove (Rhizophora mangle), the black mangrove (Avicennia germinans), the tea mangrove (Pelliciera rhizophorae), the buttonwood mangrove (Conocarpus erectus) and the white mangrove (Laguncularia racemosa) occur. The alcornoque (Mora megistoperma, a very large tree with large thin buttresses, makes an irregular appearance).
Between Piñuela Point and Uvita Point a marine abrasion platform has formed. It is connected to the mainland via a sandy bridge or tombolo, which took shape naturally through the diffraction of the waves on the rocky point. It can be visited easily at low tide. On Ballena island and the Las Tres Hermanas islets there are two species of reptiles: the green iguana (Iguana iguana), and the basilisk (Basiliscus basiliscus). Magnificent frigate birds (Fregata magnificens), white ibis (Eudocimus albus) and brown pelicans (Pelecanus occidentalis) use these islands as a roosting site.
The coral reefs are made up of five of the 18 species recorded in the Eastern Pacific. In addition to the wealth of fish and the abundance of marine invertebrates in the park waters, it is possible to see common dolphins (Delphinus delphis), bottle nosed dolphins (Tursiops truncatus) and, occasionally, humpback whales (Megaptera novaeangliae), sometimes with their young and in groups of 2 to 3. Marine turtles lay their eggs on Ballena Beach.
Ballena is on the Pacific Coast in Coronado Bay. The main access route is San José - Quepos - Dominical - Uvita - Bahía (228 km). In Dominical, there are hotels, restaurants and grocery stores, and near the park there is a boarding house. Bus services operate between San José und Uvita and San Isidro and Uvita. For more information on this national park and the Osa Conservation Area (ACOSA), call (506) 735-5036.