Although Manuel Antonio National Park is Costa Rica´s smallest national park, the diversity of wildlife in its 6.83 km2 (3 sq mi) is unequaled with 109 species of mammals and 184 species of birds Both brown-throated three toed sloth and Hoffmann´s two-toed sloth are a major feature, as are three of Costa Rica’s four monkey species — the mantled howler monkey, Central America squirrel monkey, and white-headed capuchin monkey. Black spiny tailed iguana, green iguana, common basilisk, white- nosed coati and many snake and bat species are also common in the park. Included in the 184 bird species are toucans, woodpeckers, potoos, motmots, tanagers, turkey vulture, parakeets and hawks. Dolphins can be observed there, as well as the occasional migrating whale. Scuba diving, snorkeling, sea kayaking, mountain biking, and hiking provide opportunities to experience the tropical wildlife that enriches Manuel Antonio.
Manuel Antonio is Costa Rica’s most visited park and the second would be the Poas Volcano National Park which lies very close to San Jose, the country’s largest urban area. The park’s popularity has led to development of the surrounding areas, with environmental impacts to nearby forests and beaches.
The Pacific Ocean in front of Manuel Antonio Park is also world renowned for its fishing. From November to April it is not uncommon for a typical angler to release multiple billfish in the over 100 pound range.