Between June and October, loggerhead sea turtles (Caretta caretta) come ashore at night to nest on Boa Vista's eastern beaches — particularly around Praia de Santa Mónica and the beaches south of Sal Rei. Boa Vista is one of the most important loggerhead nesting sites in the entire Atlantic, with hundreds of nests recorded each season.
Several conservation organisations based on the island run guided nighttime turtle watches. These are led by trained monitors who locate nesting females and allow small groups to observe without disturbing the animals. The experience — watching a 120kg turtle haul herself up the beach by moonlight — is remarkable. Book through one of the organisations in Sal Rei; most offer walks between July and September.