Sagay is best known as the guardian of the 32,000-hectare Sagay Marine Reserve, established in 1999. For visitors, highlights are the 200-hectare Carbin Reef (P100 entry), about 15km northeast of Old Sagay (20 minutes by bangka), and Suyac Island (P20 entry), where you can walk an elevated 400m bamboo boardwalk and kayak through the mangroves (P300).
To organise a boat, ask at the tourism office. Failing that, ask at the pier. A small boat will cost P1200 (maximum 10 people). Snorkelling equipment (P250) can be arranged at the tourist office (it's too shallow to dive). You'll see different species of giant clam, but fish are scarce indeed.