Koh Bida Nok and Koh Bida Nai are twin limestone monoliths located at the southernmost tip of the Phi Phi archipelago. Although they appear as rugged cliffs with no accessible beaches, geologically and ecologically, they are the crown jewels of the Hat Noppharat Thara-Mu Ko Phi Phi National Park. The defining feature of these islands is their complex underwater limestone structure, encompassing sheer vertical walls, submerged caves, and rocky outcrops reaching various depths. These formations provide a stable substrate for vibrant soft corals, massive sea fans, and gorgonians. The biodiversity here is so exceptionally high that it is consistently ranked among the top diving destinations in Thailand, particularly around the southern side of Bida Nok, where large marine life and massive schools of fish converge.

In terms of marine life, Koh Bida Nok is widely celebrated as a prime location for encountering Blacktip Reef Sharks, which are frequently seen in high density within the shallower areas of the southern bay. Divers also have a strong chance of spotting Leopard Sharks resting peacefully on the sandy seabed, alongside resident Green Sea Turtles. For macro enthusiasts, Koh Bida Nai offers a distinct experience with its intricate rocky crevices that shelter seahorses, ornate ghost pipefish, and a diverse array of colorful nudibranchs. The ecosystem thrives due to nutrient-rich currents that constantly feed the reef, resulting in spectacular sights such as fish tornados"—massive, swirling schools of yellowtail barracudas and batfish that provide an awe-inspiring experience for all who explore these depths.

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How to Get There

• The easiest way is to join a diving excursion or hire a long-tail boat from Koh Phi Phi Don (approx. 20-30 mins). Alternatively, speedboats are available from Krabi Town or Ao Nang beach.

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Travel Tips

• Always check the weather forecast and sea conditions before departure.

• The best period for clear and calm water is November to April.

• For the best chance to see blacktip reef sharks, dive the south bay of Bida Nok.

• Bring an underwater camera with a deep-water housing to capture the scenery.

• Use only reef-safe sunscreen to protect the fragile marine ecosystem.

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Admission Fees:

• Thais: Adult 40 THB, Child 20 THB.

• Foreigners: Adult 400 THB, Child 200 THB.

Opening Hours:

• Daily from 07:00 – 18:00 (Subject to tour boat schedules).

• Seasonal Opening: Generally open year-round. However, access may be temporarily restricted or closed during the monsoon season (May – October) if weather conditions are deemed unsafe by the National Park Department.