5 snorkelling islands ordered by clearest water
The southern islands off Koh Chang inside the national park — which one has the clearest water, which is closest, which is quietest.
1
If you only take one boat out, make it Koh Rang. It sits inside the Mu Ko Chang National Park, south of the main island, and it's the clearest water and the healthiest coral in these waters. The big boats anchor at spots around the island and let you drop in to look at coral and shoals of fish.
There are several snorkelling spots around Koh Rang, the water shallow and clear enough to see the coral from the surface — good for beginners and keen snorkellers alike. Honestly, it's further out than the other stops, roughly 1–1.5 hours each way on a big boat, and you pay the marine park fee because it's a conservation zone. In return the water is clearer and the coral better than the closer sites, which makes it well worth the journey.
2
Koh Wai is a small island south of Koh Chang with very clear water and a shallow reef right off the beach — you can wade in from the sand and snorkel without heading out by boat. It's a favourite with beginners and families because the water is shallow, clear and the waves are gentle.
The mood on Koh Wai is quiet and unhurried, with just a few simple places to stay. Most tours stop here as one leg of a multi-island trip, giving you time to swim and have lunch — some travellers even stay a night to switch off completely. If you want clear water off the sand without a long boat ride, Koh Wai delivers.
Koh Yak (some tours split it into Koh Yak Yai and Koh Yak Lek) is a small rocky island in the Koh Rang cluster. Big boats often anchor here for a coral stop on the way to Koh Rang — the water around it is clear, with coral and shoals of fish to keep you happily occupied.
Koh Yak isn't a landing where you walk around; it's a snorkelling stop out on the water, where the boat moors and you drop straight in. The upside is it's usually quieter than the headline spots, the water a touch deeper than off a beach, so put a life jacket on and float over the coral from the surface. If your trip goes to Koh Rang, there's a good chance you'll stop at Koh Yak too — a bonus that's every bit as pretty.
Koh Mai Si (Koh Mai Si Yai and Koh Mai Si Lek) is another small island in the Koh Rang cluster that tours often visit. The water around it is shallow and clear, and on some trips there's a little white-sand beach to step out onto for photos — it can feel like your own private island.
What stands out about Koh Mai Si is the shallow, clear water that suits beginners — easy snorkelling without going deep, gentle waves, and fine for kids. Multi-island tours tend to pair Koh Mai Si with Koh Rang and Koh Yak, since they're close together in the same park, so you get several snorkelling stops in one day — good value for the time spent on the boat.
Koh Kradad lies to the east of Koh Chang and feels different from the Koh Rang cluster — a quiet island with a long white-sand beach, shallow clear water, and, unusually, a herd of deer that roam the island, which kids love. Some operators run Koh Kradad as a separate trip or pair it with nearby islands to the east.
Koh Kradad suits people who want a calm island, a pretty beach and clear water more than serious coral snorkelling (the reef isn't as good as Koh Rang). You come to walk the sand, swim in the shallows, see the deer, take photos and unwind. Honestly, this isn't the main snorkelling trip — but if you have the time and fancy a change of scene from the southern islands, it's a charming option.
Koh Chang snorkelling tours come in two main shapes — the four-island trip with Koh Rang as its main stop (clearest water, but you pay the park fee and the boat ride is longer), and the three-island trip to Koh Wai, Koh Klum and Koh Laoya, which are closer (about 40 minutes), more relaxed, and usually don't carry that marine park fee.
Choose the wooden big boat if you want to save money and aren't in a hurry (out in the morning, back in the evening, a few more people aboard), or a speedboat if you want to get there fast, hit more stops and spend more time in the water. Honestly, if you've come to snorkel coral properly, pick a trip that includes Koh Rang; if you just want easy island time with clear water off a beach, the Koh Wai / three-island trip is plenty.