The Hat Noppharat Thara–Mu Ko Phi Phi National Park encompasses 387 square kilometres of Andaman coastline, but four limestone outcrops between Ao Nang and Railay define the archipelago's most concentrated snorkeling circuit.
Phra Nang Cave Beach, Tup Island, Chicken Island and Poda Island lie within a six-kilometre radius, each rising from coral gardens no deeper than twelve metres at low tide. Thai fishermen charted these channels with bamboo longboats in the 1950s; tourism arrived in 1982 when the park gazetted the islands as protected reef zones, capping daily vessel numbers to thirty per anchorage.
Private longtail boat krabi charters emerged in the late 1990s as Ao Nang's backpacker economy matured into a year-round resort corridor. Traditional ruea hang yao hulls, hewn from single teak or takian logs and powered by repurposed truck engines, carry six to eight passengers at fifteen knots. Speedboats entered the market in 2006, cutting transit time to Chicken Island from forty minutes to twelve. Both vessel classes operate under park-ranger oversight; skippers radio the Hat Noppharat Thara headquarters each morning to confirm tide windows and mooring allocations. The 200-baht conservation fee, collected on-site by uniformed rangers, funds reef-restoration projects and plastic-removal patrols across the park's seventy-kilometre coastline.
Phra Nang's karst overhang shelters a tidal cave shrine where Andaman mariners have left carved phalluses and incense bundles since the Ayutthaya period. Tup Island and Chicken Island connect by a fifty-metre sandbar visible only during the October–April northeast monsoon's low tides; the corridor closes when swells exceed one metre. Poda Island's northwest beach holds thirty mooring buoys for longtails, while speedboats anchor in deeper water off the eastern cape. Coral health surveys conducted in 2024 by Kasetsart University marine biologists recorded ninety-three hard-coral species across the four-island circuit, with staghorn and brain-coral colonies rebounding along Chicken Island's western slope.
Departures run from 08:00 to 09:30, before the midday heat concentrates tourist traffic. Private charters bypass the group-boat queues at Noppharat Thara Pier, launching instead from beachfront operators in Ao Nang. The 4 island tour krabi private boat itinerary allocates four to five hours afloat, depending on snorkeling duration and sandbar timing. Rangers enforce a 16:30 return deadline to protect nesting-seabird curfews on Poda's southern cliffs.
6 hr
