Koh Bida Nai & Nok / PhiPhi

Koh Bida Nai and Koh Bida Nok are twin islands at the southern tip of the Phi Phi archipelago that together create one of the most exciting and productive dive areas in the Andaman Sea. These dramatic limestone pinnacles, rising vertically from the deep blue water, offer beginner-accessible diving that punches well above its weight in terms of marine encounters, with leopard sharks, blacktip reef sharks, and occasionally whale sharks drawing divers to these iconic formations. The two Bida islands sit side by side in the open water south of Phi Phi Leh, their cliff faces plunging underwater to create walls and slopes rich with marine growth. Koh Bida Nok, the outer island, tends to have more dramatic wall diving and current exposure, while Koh Bida Nai, the inner island, offers slightly more sheltered conditions with excellent coral gardens. Together they provide a range of diving experiences that can be tailored to different experience levels. Leopard sharks are the star attraction at the Bida islands, particularly on the sandy flats and ledges where these beautiful spotted sharks rest during the day. Finding a leopard shark lying motionless on the sand, its elegant markings standing out against the pale substrate, is a reliable highlight that draws divers back to these islands repeatedly. Blacktip reef sharks patrol the reef edges with more purposeful energy, and during certain periods whale sharks pass through the area on their migratory routes. The reef systems around both islands are in excellent health. Hard corals cover the shallower sections in dense gardens, while the deeper walls are decorated with spectacular soft corals, sea fans, and barrel sponges. The vertical limestone creates natural overhangs and small caves that shelter concentrations of marine life, including schools of glassfish that form shimmering curtains in the shaded spaces. Fish diversity is outstanding. Schools of barracuda and trevally patrol the open water between the islands, while the reef sections host the full spectrum of tropical species from tiny blennies to large Napoleon wrasse. Moray eels of several species occupy the limestone crevices, and octopus navigate the rocky terrain with their characteristic color-changing ability. The macro life includes nudibranchs, mantis shrimp, and the ornate ghost pipefish that make the Bida islands a macro photographer's paradise. The Bida islands are typically dived as part of day trips from Phi Phi Don or Phuket, with the journey from Phi Phi taking just fifteen to twenty minutes. The short travel time means maximum time in the water, and most trip operators visit both islands over the course of a diving day. Koh Bida Nai and Nok represent Phi Phi diving at its best. The combination of shark encounters, exceptional reef health, and the dramatic limestone scenery creates a diving experience that ranks among the finest in Thailand and fully justifies the Phi Phi Islands' reputation as a world-class dive destination.