Phi Phi & the King Cruiser · Thailand · Reef · Coral garden
Koh Bida Nai
Swim-throughs behind walls of glassfish, and no current
Photo: Christophe95 · CC BY-SA 4.0
Koh Bida Nai is the inner of the two Bida rocks, a sheltered site of large boulders and rocks forming swim-throughs hidden behind walls of glassfish. There is normally no current, dives run 10 to 25 m, and a shallow coral garden makes the safety stop easy. Leopard sharks and blacktip reef sharks are the regular sightings.
Also known as Ko Bida Nai, Bida Nai Inner Rock.
Where it is and how deep
7.6578° N, 98.7678° EPublished position for this site.
The dive
Bida Nai is the sheltered sister of Bida Nok and it dives like it. There is normally no current, so the site is worked slowly between 10 and 25 m around large boulders and rocks that create interesting swim-throughs, most of them hidden behind walls of glassfish thick enough that you find the gap by swimming into it. It is a forgiving site for divers still sorting out their buoyancy.
Head southeast away from the main island to find Fantasy Reef, a smaller secondary submerged reef. This is a good spot to look for leopard sharks and blacktip reef sharks, and turtles, groupers and trevally are all part of the regular cast on the site. With no current to fight, the swim out and the swim back are both unhurried.
The rest of the dive is small-scale: clownfish in the anemones, cuttlefish over the rock, lionfish and pipefish in the cracks, and many nudibranchs. Divers who slow down find ornate ghost pipefish, a boxer shrimp or a seahorse. Finish in the shallow coral garden, which serves as an ideal safety stop location and is the easiest part of the site to linger over.
Marine life and season
- Reef sharks
- Sea turtles
- Octopus & cuttlefish
- Nudibranchs
- Groupers
- Trevally & jacks
- Macro critters
- Reef fish swarms
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prime | Prime | Prime | Prime | Good | Fair | Fair | Fair | Fair | Good | Prime | Prime |
Season follows Phi Phi & the King Cruiser: Nov–Apr is the dry season with the calmest, clearest water; the south-west monsoon from May to October brings swell and rain.
Know before you go
- The site can be crowded during peak season, with several groups on the same boulders; stay close to your guide in the swim-throughs.
Photos from Koh Bida Nai
Donald Davesne · CC BY 4.0
portioid · CC BY-SA 4.0
portioid · CC BY-SA 4.0
Dive videos
Diving Koh Bida Nai / Andaman Sea (Phuket): with THE DEE'S · KandU.letsgo on YouTube
Questions divers ask
Is Koh Bida Nai good for beginners?+
Yes. There is normally no current, normal diving depth is 10 to 25 m, and the shallow coral garden makes for a straightforward safety stop on the reef.
What can you see at Koh Bida Nai?+
Leopard sharks and blacktip reef sharks are the regular sightings, along with turtles, cuttlefish, groupers, lionfish, pipefish and many nudibranchs. Ornate ghost pipefish, boxer shrimp and seahorses reward patient divers.
Sources
- Koh Bida Nai — Divezone
- Diving in Thailand — Wikivoyage
- Ko Bida Nai (OpenStreetMap) — OpenStreetMap
Photo credits
- The two limestone Bida rocks rising from the sea, seen from a boat near Ko Phi Phi Le by Christophe95, CC BY-SA 4.0, via Wikimedia Commons
- Painted spiny lobster with long blue antennae tucked among boulders by Donald Davesne, CC BY 4.0, via Wikimedia Commons
- Red and white banded dancing shrimp perched on coral by portioid, CC BY-SA 4.0, via Wikimedia Commons
- Black and grey banded yellow-lipped sea krait resting on sand between rocks by portioid, CC BY-SA 4.0, via Wikimedia Commons
In The Logbook
- Where to see reef sharks on your first divesBig animals · 14 min read
More dive sites in Phi Phi & the King Cruiser
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Reef
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Wall
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Pinnacle
A multi-headed pinnacle off an uninhabited islet, around 15 m
Wall
Underwater cliffs to 21 m, cut by small caverns and swim-throughs
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