The park encompasses the Arenal Volcano, the most active in the country, which was believed to be dormant until a major eruption in 1968.

In and around the park are various lodges and hotels, some with their own hot springs, and others focused on the wildlife of the area.

The park lies within the Arenal Huetar Norte Conservation Area, protecting eight of Costa Rica's 12 life zones and 16 protected reserves in the region between the Guanacaste and Tilarán mountain ranges, and including Lake Arenal.

This includes one of the country's most elusive and beautiful birds, the endangered resplendent quetzal.

The park also has a strong showing of plant life, including orchids, heliconias, ferns, laurel, cirri, guayabo de monte, palms, bromeliads, and strangler figs.