Coast through the jungle on a zip line tour along the Montezuma River ($65 including transportation). Over the course of two hours, you’ll cross nine lines, spot parrots and iguanas from 80 feet above the forest floor, and stop for quick dips in pools beneath tumbling waterfalls. Afterward, you’ll have time to browse the patchouli-scented shops in the hippy-backpacker town of Montezuma before heading back to Santa Teresa.
Wake up early to spend a full day snorkeling and hiking on secluded Tortuga Island, a 50-minute boat trip from Montezuma ($55 including transportation from Santa Teresa). En route, spot dolphins, manta rays, and humpback whales; on the island, join a guided snorkeling tour before a lunch of grilled chicken and fish is served with beer. You can take part in a second session in the afternoon, but the hike to the top of Tortuga is worth it for views of the Gulf of Nicoya and surrounding islands.
Hike around Cabo Blanco National Park ($6; open 8 a.m.-4 p.m. Wed. through Sun.), the five-square-mile refuge that helped establish Costa Rica as a destination for eco-tourism when it was established in 1963. Grab a self-guided trail map at the park entrance before hiking down to the white-sand beaches Playa Balsita and Playa Cabo Blanco. For a more strenuous hike, take the 3-mile Sueco Trail, which leads from the reserve’s northern to southern tip.