Diani Beach has several PADI-certified dive centres offering reef dives on the fringing coral reef, which runs parallel to the beach a short boat ride offshore. The reef is in reasonable health and holds a wide range of marine life: reef fish in abundance, sea turtles, moray eels, lionfish, and rays. Deeper sites further offshore offer better coral structure and the possibility of whale sharks during the right season.
All the main dive operators run introductory dives for beginners as well as full PADI courses. The water is warm year-round — a thin wetsuit or swimsuit is sufficient — and visibility is generally good outside the rainy seasons. Sunrise and two-tank morning dives are the standard format; night dives can be arranged with advance notice.