Hat Noppharat Thara–Mu Ko Phi Phi National Park, gazetted in 1983, protects 387 square kilometres of the Andaman Sea between Krabi's mangrove coast and the limestone towers of Phi Phi. The park's conservation zone includes Poda Island, Chicken Island, Tup Island and Mor Island—four karst formations that draw visitors year-round for their shallow reef systems and seasonal sandbars. A 400-baht per-person conservation fee, introduced in 2019, funds mooring-buoy installations and waste-removal programmes across the archipelago. The krabi island tour package market centres on these four islands because they lie within a forty-minute radius of Ao Nang pier, making them accessible to traditional longtail boats whose shallow draught suits the tidal flats. Speedboat operators serve the same circuit in half the time, departing from the same Hat Noppharat Thara staging point. Both vessel types navigate coral channels that reach three metres at high tide, revealing species catalogued by the Department of Marine and Coastal Resources: staghorn Acropora, brain corals, sergeant majors, parrotfish and occasional blacktip reef sharks. The sandbar linking Tup and Mor islands emerges fully only during the December-to-April dry season, when tidal amplitude reaches 2.8 metres. Krabi's island-hopping infrastructure expanded significantly after the 2004 tsunami, when rebuilt piers incorporated deeper berths and concrete staging areas. Longtail captains, many of whom hold third-generation fishing licences, now operate under park-service quotas that limit daily departures to 120 vessels. Speedboat operators, licensed since 2011, follow separate mooring protocols to reduce propeller damage to seagrass beds. Both fleets depart between 08:00 and 10:00 to avoid midday thermal stress on shallow reefs, returning by 16:30 when the park office closes its Ao Nang checkpoint. The circuit typically includes two snorkelling stops, a beach lunch on Poda's western shore, and a sandbar walk if tides permit. Visitor numbers peaked in 2019 at 1.8 million annual arrivals across the four-island corridor, prompting the park service to introduce staggered departure slots and seasonal reef-rest periods. Krabi island tour package tickets now include the conservation fee, eliminating separate transactions at each landing. The longtail-versus-speedboat choice remains the defining decision for most visitors: traditional wooden hulls offer shade and slower passage, while fiberglass speedboats trade comfort for efficiency and access to the outer Seven Islands circuit when conditions allow.