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Diving Thailand – Dive Sites Thailand – Scuba Diving Similans
Name Bida Nai Koh Phi Phi
Depth 6-28m
Vis 5-35m
Water Temp 26-30c
Level Beginner+
Our Rating 4 Stars
Best Time to Visit All Year
GPS 07-39-28N 98-46-02E
  Map of Local Dive Sites
Bida Nai Leopard Shark

Bida Nai (sometimes spelt Bidah Nai) is by far one of the best dive sites local to Koh Phi Phi, along with it's close neighbour Bida Nog. Bida Nai is famed for the many Leopard Sharks it is home to and it's not abnormal to see three or more, on a single dive. They rest in the sand pumping water over their gills to breathe. They also mate here and it's possible to see two or more males competing for the affections of a lone female, biting her pectoral fins and entwining tails in an effort to have Shark sex.

Bida Nai is a small limestone island, which is possible to encircle in a single dive. A better dive plan would be to move much more slowly so as not to miss the many delights this sight has to offer. Expect to find and see much more marine life here than you would at Phukets dive sites, although quite often the visibility isn't quite as good. As to why there are more species of fish and marine life here - it's a bit of a mystery, as Phuket is located only 42km away to the west.

There is a fantastic swim through at 14 metres to the south west of the dive site, which often seems like a dead end due to the high density of Glassfish that crowd the entrance attempting to hide from larger predators. Lionfish and Bearded Scorpionfish also congregate here picking off the unlucky fish bait one by one. There is also another, longer swim through close to the actual island, at a depth of about 7 metres. Be wary of entering if there's a swell as the surge can make it difficult to get through without clipping corals, damaging them in the process.

Bida Nai also has a shallow bay to the south east of the site, which is great for beginners and inexperienced divers. It's an ideal spot for the dive boat to drop eager divers. Continue the dive according to the current, and as you progress the slopes disappear until you're left diving the sheer walls, which are literally covered with corals and huge fans. It's possible to find Seahorses and Ghost Pipefish here, if you're guide knows just where to look. Octopus, Cuttlefish and Blacktip Sharks can also be found at this one dive site.


To the southwest you can move out deeper over the sand and patches of Staghorn coral past Kuhl's Stingrays and possibly a Leopard Shark. Continue in this direction and you will come to a separate reef system known as Fantasy Reef. This is the best part of Bida Nai. The concentration of marine life here is breath taking. Pelagics school overhead. Huge schools of Yellow Tail Barracuda patrol, Giant Trevally and Jacks flash past, huge shoals of Snappers stay low close to the reef, shimmering in carpets of crimson yellow as you approach. Whalesharks are often spotted at Bida Nai during the high season and more often than not cruising over Fantasy Reef. Currents can be from weak to very strong here, but even in strong currents there are spots close to the reef that are protected. In very strong currents, it may not be possible to visit Fantasy Reef.