Koh Mak is flat and compact, so its beaches are easy to sample in a day on a bicycle — which is the best way to work out where to spend the rest of your trip. The water is calm and the sand pale, but the island earns trust by being honest: a couple of these are genuinely lovely swimming beaches, and a couple are better for a look than a dip. Here is the rundown.
Ao Kao: the main event
Ao Kao on the south-west is the beach most people come for and most should base on. It is the longest stretch with the easiest, most swimmable sand, and behind it runs the island's only real strip of restaurants, cafés, and bars. Calm, shallow, and gently shelving, it suits swimmers and families, and it faces west enough for a good evening light. If you remember one Koh Mak beach, make it this one.
Ao Suan Yai: the long sunset beach
Ao Suan Yai on the north-west is the other headline — a quiet two-kilometre arc looking out toward Koh Chang, with the island's best sunset. It is beautiful at the right tide, though parts go shallow and can pick up seagrass at low water, so it rewards a mid-to-high tide swim. Fewer places to eat nearby, more space, better views.
The smaller bays: Ao Pra, Ao Lom and the coves
Around the quieter coasts, small bays like Ao Pra and Ao Lom give you near-empty sand and a real sense of having the island to yourself. They are cycle-and-explore beaches rather than full-service ones — bring water, expect little or nothing open, and treat them as the reward for getting on a bike.
Ao Nid: a pier, not a swim
Ao Nid on the south-east is one of the island's arrival piers, set among mangroves rather than swimming sand. It is worth knowing so you do not book a beach holiday next to a working jetty expecting a swim — pass through it, don't plan around it.
A word on tides and seagrass
Like much of this coast, parts of Koh Mak go shallow at low tide and some beaches carry seagrass close to shore. That is a sign of a healthy, undeveloped marine environment, not a problem to fix — but if a clear swim straight off the sand matters to you, favour Ao Kao and time it for higher water.
Frequently Asked Questions
Which is the best beach on Koh Mak?
Ao Kao on the south-west — the longest, most swimmable beach with the most behind it. Ao Suan Yai is the other standout, longer and better for sunset but shallower in parts. Between them they cover almost everything most visitors want.
Can you swim everywhere on Koh Mak?
Not equally. Ao Kao is the most reliably swimmable; Ao Suan Yai and some smaller bays go shallow and can get seagrass or weed at low tide, which is natural and harmless but not ideal for a swim. Check the tide and aim for mid-to-high water.
Are Koh Mak's beaches crowded?
No. Koh Mak is one of the quietest developed islands in Thailand, and even Ao Kao in peak season stays calm. The smaller beaches are often empty. If you want solitude on sand, this island delivers it easily.
Is there a sunset beach on Koh Mak?
Ao Suan Yai on the north-west is the sunset spot, with open water and the outline of Koh Chang on the horizon. Ao Kao also faces roughly west and catches good evening light, so you are well placed for sunset from either main beach.
