Tortuguero National Park on the Caribbean Coast is accessible only by boat or plane, is one of the wettest areas in the country and offers something different than the rest of Costa Rica. The park is an extremely important breeding ground for the green sea turtle and as a result, turtle watching is the main activity here.
While there are many beaches, the coastal area is not suitable for swimming as the surf and currents are rough and strong. Sharks are common. Hundreds and even thousands of green and leatherback turtles can be viewed (guides are necessary) nesting and laying eggs on the beaches overnight.
Conservation efforts have increased the number of turtles nesting in the area. From the hiking trails or boat rides along the canals, it's possible to spot monkeys, sloths, and kinkajous.