The Aviarios Sloth Sanctuary, on the Estrella River about 20 minutes north of Puerto Viejo near Cahuita, was the first dedicated sloth-rescue centre in the world. Orphaned and injured sloths arrive here from across Costa Rica; those that recover are released into the surrounding forest, those that can't stay in the sanctuary's enclosures and garden.
Two-hour tours include a slow canoe ride along the river through swamp forest — much better than a typical zoo experience because the wild sloths in the trees outnumber the captive ones. Book ahead, especially in high season. The sanctuary funds the centre's rescue work and is one of the most popular day trips from Puerto Viejo.