Ilha de Areia Vermelha is an island of red sand that emerges off the northern beaches at low tide for roughly half the days in each month. Boats park around the island and the party lasts until the tide comes in. You can catch a boat out there for R$30 to R$35 from Praia de Camboinha, 15km north of Tambaú. Organize the trips in one of the beachside bars. Some boats have rowdy bars while others are more relaxed affairs.
Check in at the tourism office the day before to find out if a trip is going.