The best diving season around Koh Chang is roughly November to April, when the west coast sea is calmer and clearer. December to February is the most reliable stretch. Here is the year in the water, month by month.
The best diving season around Koh Chang is roughly November to April, when the sea on the west coast is calmer and clearer. December to February is the most dependable stretch, with dry weather and a sea that is calm and clear. From about June to September the water is often rough on this side of the island, and boat trips can be called off.
One honest note first. We are a small resort, not a dive centre, so we do not run dives ourselves. What we can tell you is how the sea behaves through the year, because we watch it from the deck every day. Dive centres on the west coast run fun dives and courses around the same reefs that the snorkelling boats visit, including the protected waters around Koh Rang.
The year in the water
This is how the sea and the crowds change through the year, as we see it from Lonely Beach.
- November: rain easing, the sea calming, crowds building.
- December to January: dry and breezy, the sea calm and clear. This is also the busiest time.
- February: dry and warming, the sea still calm and clear, and the island busy.
- March to April: hot and mostly dry, with a warm, calm sea.
- May: hot, with the first storms. The sea starts to change.
- June to September: rainy and lush, with the sea often rough on the west coast. This is the quietest time.
- October: the rain gradually easing and the sea settling.
The clearest water near Koh Chang is to the south, around Koh Rang, which sits inside the marine national park. November to February is when visibility there is usually at its best. The calm that suits snorkellers is the same calm you want underwater.
Right now: early November
Today is 2 November, which is the turn of the season. The rain is easing and the sea is calming, but it is not yet calm every single day. The island is still deep green, and the crowds are only just starting to arrive.
If you are here now and want a day on the water, do it early in your stay. Keep a spare day in reserve, because a boat trip depends on the sea, not on your calendar. By December the odds are much better. For more on how the weeks unfold, our month by month weather guide has the detail.
Diving in the green season
From roughly June to October the sea decides. Some days the boats run beautifully, and other days they are cancelled because of the waves. If your dates are fixed in these months, treat any dive or snorkel day as a bonus rather than a promise.
The same goes for the islands further south. From Bang Bao, boats also connect Koh Chang with Koh Wai, Koh Mak and Koh Kood, but some of those services only run in high season. Check the schedule before you build a plan around them.
Rough water does have a flip side. The jungle is at its greenest, the waterfalls are full and the island is peaceful. If you want both, the guide to high season and green season will help you choose.
What to ask before you book
Whoever you book with, a few questions save surprises on the day.
- Where does the boat leave from? Most trips to Koh Rang go from Bang Bao or Kai Bae, usually around 09:00 to 09:30.
- How long is the crossing? Reaching Koh Rang takes 30 to 60 minutes, depending on the boat.
- What is included? On snorkelling trips the marine park fee of ฿200 is usually paid on top. Ask your dive centre what its price covers.
- Speedboat or wooden boat? Speedboats are faster but bounce more on choppy days. Bigger wooden boats are slower and gentler if you get seasick.
- What happens if the sea is rough? Ask whether you can move the day or get a refund.
- If you want a course rather than a single dive, ask how many days it needs, so you can plan around it.
Tell the team at Paradise Cottage what you have in mind and we will say what we can arrange. A tour desk can book boats for you, and it is better to ask than to guess.
If you only want to snorkel
You do not need a certificate to see the reef. Koh Rang is the most popular snorkelling destination in the area. Because it lies inside the marine park, the reefs are better protected, with hard and soft corals and schools of reef fish. Masks and snorkels are normally included, and fins often rent for around ฿100.
A cheaper option is the three-island trip to the Koh Wai area, which usually leaves about 10:30 and returns around 16:00. Our guide to snorkelling Koh Rang and island hopping explains how the days work.
Wherever you swim, treat the coral gently. Never stand on it or touch it, keep your fins up in shallow water, and wear a life jacket if you are not a confident swimmer.
The shore in front of the resort is rocky, which is lovely for sunsets but not for diving or paddling. The boats leave from elsewhere, and you come home to the pool, a hammock and the deck. Check-in is from 14:00. In high season, October to May, a Front Sea View bungalow is an estimated ฿1,500 to ฿2,500 a night, and a Garden Bungalow ฿1,000 to ฿1,800. Message the team on WhatsApp for the actual price.
Quick answers
When is the best time to dive around Koh Chang?
Roughly November to April, when the sea is calmer and clearer. December to February is the most dependable stretch, with dry weather and a calm, clear sea.
Can you dive on Koh Chang in the rainy season?
It depends on the sea. From about June to October the west coast is often rough, and some boat trips are called off on windy days. Keep your plans flexible and book early in your stay so you have a spare day.
Where do boats to the Koh Rang reefs leave from?
Most leave from Bang Bao or Kai Bae around 09:00 to 09:30. The crossing to Koh Rang takes 30 to 60 minutes, depending on the boat.
Do I need to be a diver to see the reefs?
No. Koh Rang is the most popular snorkelling destination in the area, with masks and snorkels normally included. The marine park fee of ฿200 is usually paid on top of the trip price.
