Koh Doc Mai Diving Guide: Depth, Season & Who It Suits
Koh Doc Mai is a Phuket wall and macro dive site. See depth, visibility, best months, cave rules, trip options and who should skip it.
On this page
Last updated November 2026: Koh Doc Mai is a small limestone island between Phuket and the Phi Phi Islands, dived from a boat for its east wall and its macro life. Intermediate divers get the most from it, and many operators schedule it as the last dive of a King Cruiser and Shark Point day. Use this guide to decide whether it earns a slot next to the other 8 Phuket Dive Sites: Racha, Shark Point & Wrecks.
Featured image (Ko Muk, a neighboring island, shown for illustration; not Koh Doc Mai): Marcin Konsek, CC BY-SA 4.0, via Wikimedia Commons.
Koh Doc Mai at a glance
Koh Doc Mai, also spelled Koh Dok Mai, means "Flower Island" in Thai. It is a limestone rock that rises out of the Andaman Sea, and you dive it from a boat. There is no access to the island itself, so it is not a beach stop. Figures below are operator-reported ranges, and they differ by side of the island and by season.
| Detail | What operators report |
|---|---|
| Site type | Wall dive with macro life and two caverns |
| Depth range | 5–32 m (16–105 ft); most dives stay well above the maximum |
| Level | Typically intermediate |
| Entry | Boat entry, no landing |
| Visibility | About 3–25 m depending on season, tide and side |
| Water temperature | 27–30°C (81–86°F) |
| Best months | November to April |
What makes Koh Doc Mai worth diving
Its east flank drops as a sheer limestone wall. Yellow tube corals and gorgonian sea fans cover the rock face. Two caverns open on the east side, known as the big cave and the small cave. West of the island, a gentler slope of hard coral runs from about 12–20 m (40–66 ft). Cracks and crevices at every depth shelter small animals. Divers who move slowly and check each crevice see far more than divers who cruise along the wall. That makes it a macro site first and a scenery site second.
Is Koh Doc Mai right for you?
Most operators rate it intermediate, mainly because tidal currents can run hard along the wall. You need to be comfortable drifting with the flow and holding your depth beside a vertical drop. Divers with only an entry-level certification, such as the one described on PADI's Open Water Diver page, should ask the operator whether the day's conditions suit them. Skip the small cave unless you hold cavern training. It is narrow and long. If you want a different profile, look at Koh Racha Diving Guide: Racha Yai vs Racha Noi or the smaller Racha Noi site. These qualitative comparisons reflect our editorial assessment of the reported facts.
| Site | Best fit | Main trade-off |
|---|---|---|
| Koh Doc Mai | Macro-minded divers who like walls | Visibility and current vary |
| Shark Point | Divers hoping for leopard sharks and soft-coral pinnacles | Currents set the route |
| Anemone Reef | Photographers who like a pinnacle covered in anemones | Depth runs 5–30 m |
| King Cruiser wreck | Advanced divers comfortable at depth | Passenger deck sits at 18–22 m |
| Racha sites | Divers wanting a separate day away from the combo route | Needs its own trip |
- Mistake: fighting the current instead of drifting with it.
- Mistake: entering either cavern without cavern training.
- Mistake: diving it with no interest in small subjects.
- Mistake: relying on it as your only dive on a rough-sea day.
- Mistake: touching crevice life for a better photo.
- Mistake: drinking alcohol before a dive day. Some operators bar anyone who has drunk alcohol from the water.
Best time to dive Koh Doc Mai
November to April is the favoured window, which covers the northeast monsoon. Seas are calmest and visibility is at its best in those months. Dive logs from May to October show no "best" months. That does not mean the site shuts. Rough seas can cancel or reshuffle trips, and tide and weather can change an itinerary at short notice. Visibility reports range from 3 m on a poor day to 25 m on a good one. Treat any single number as a hope, not a promise.
What you may see
Macro life is the draw. Sightings are commonly reported but never guaranteed, and some species are seasonal. Look into crevices and across sea fans rather than out into the blue.
| Look for | Notes |
|---|---|
| Tigertail seahorse | Commonly reported on the wall |
| Ornate ghost pipefish | Commonly reported; move slowly |
| Harlequin shrimp | Commonly reported |
| Nudibranchs | Often seen, including around the 5 m safety-stop depth |
| White-eyed morays | Small ones in crevices |
| Dancing shrimp | Groups of 10 or more are reported |
| Zebra shark | Seasonal, not guaranteed |
| Leopard shark, barracuda | Occasional, in the blue or on the sand |
How to dive Koh Doc Mai safely
Dive within your training and follow the operator briefing. Drift along the wall with the current rather than swimming against it. Check depth and buoyancy often while you hunt for macro subjects, because a vertical wall hides how far you have sunk. Stay out of the caverns without overhead-environment training and the right equipment. Keep your hands off the rock and the sea fans. Lens choice matters too. A macro lens suits the crevices, while a wide-angle lens suits the sea fans and the wall itself.
Getting there and what a trip looks like
Boats leave from Phuket, and the usual return leg ends at Chalong Bay. One operator's combo day pairs the King Cruiser Wreck Phuket: Depth, Certification & How to Dive It and Shark Point with Koh Doc Mai. Pickup runs 07:30–08:00 from Patong, Karon and Kata, and the boat departs at 08:15. Koh Doc Mai is the third dive, around 14:00. You are back at your hotel around 17:30. Order varies with tide and weather. Prices and hours checked November 2026. That operator quotes full gear rental at ฿900 per person, covering BCD, short wetsuit, regulator, mask and fins. A private guide is ฿8,000 per day. Nitrox 32% is included only for certified divers.
Pickup runs 07:30–08:00 from Patong, Karon and Kata. Rough seas can cancel or reshuffle trips, so keep a flexible day in mind.
| Trip style | What to expect |
|---|---|
| Combo day | King Cruiser, Shark Point and Koh Doc Mai; Koh Doc Mai usually last |
| Racha day | A separate trip; ask the operator for dive count and price |
| Private guide | ฿8,000 per day at one operator; lets you set a macro-focused plan |
- A combo day works well if you want three contrasting sites.
- A private or macro-focused day suits photographers who need time at the wall.
- Non-divers cannot land on the island. Ask the operator whether snorkeling is offered on your trip.
Koh Doc Mai on the map
Koh Doc Mai sits between Phuket and the Phi Phi Islands in the Andaman Sea. Your operator confirms the exact entry point on the day, since currents decide where the boat ties up.
Nearby sites to pair it with
Three neighbors share this route. Shark Point is known for leopard sharks, and our Shark Point guide covers its pinnacles. Anemone Reef Phuket: Dive Site Guide for Planning a Trip is a pinnacle with its top at 5 m, dropping to 30 m. The King Cruiser is an 85 m ferry lying near Anemone Reef, with a passenger deck at 18–22 m. Penetration is considered unsafe, so stay outside the structure. Browse the full Phuket dive site list to build a longer plan.
Anemone Reef is a pinnacle with its top at 5 m, dropping to 30 m. Its shallow top matches the 5 m safety-stop depth where nudibranchs are often seen.
Notes for your next dive trip
Optional updates to our Thai diving guides.
You might also like
Continue reading
More guides you'll find useful
.jpg){kind=link}