Hin Daeng & Hin Muang (Koh Lanta)

These twin offshore gems are famed for sheer walls, photogenic purple soft corals, and pelagic fly-bys. While mantas are the headline act, whale sharks also patrol the perimeter in late season when plankton builds. Depths drop well beyond recreational limits and currents can be strong, creating downcurrent zones at edges and corners. Operators typically require Advanced Open Water, recent dives to 30 meters, an SMB, and calm-sea forecasts. Divers with good gas management and trim are rewarded with dramatic topography, barracuda tornadoes, and the chance of a lifetime when a spotted giant appears out of the blue. Day trips run from Koh Lanta and sometimes Phuket in very good conditions.