Wrecks, coral gardens, and slow-island beach days in Thailand's eastern Gulf
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Overview
Trat Province's island chain delivers an easy, multi-island Thailand dive trip without long travel days. Base on rainforest Koh Chang for boat diving and the headline HTMS Chang wreck, then slow down on tiny Koh Mak or palm-lined Koh Kood for shallow reefs, beach time, and sunset sessions. Much of the archipelago sits inside Mu Ko Chang National Park, so day trips often combine coral gardens, beginner-friendly depths, and clear-water snorkeling. Conditions are generally warm year-round, with the driest, calmest seas from November to April. May to October brings heavier rain and rougher crossings, but also greener jungle and stronger waterfalls.
Koh Chang, Koh Mak, and Koh Kood sit on the east side of the Gulf of Thailand. Reefs here are mostly hard-coral gardens, gentle slopes, and boulder patches, with occasional swim-through style structure at pinnacles. Visibility is variable, but on calm high-season days you can get surprisingly clear water for the Gulf.
Many snorkel and dive trips operate inside Mu Ko Chang National Park. Expect to pay the park entrance fee (sometimes collected by rangers on the islands) and keep the receipt for the day.
Koh Chang adds jungle and waterfalls to beach days, Koh Mak is made for bikes and slow afternoons, and Koh Kood is a "do less, better" island of beaches, river swims, and sunset viewpoints.
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Last updated: January 23, 2026 • 16 sources
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Trip callouts
Much of the island chain sits inside Mu Ko Chang National Park, protecting coral reefs around islands like Koh Wai and the Koh Rang group.
The HTMS Chang Wreck delivers big structure and fish life for advanced depth profiles, while nearby reefs keep the trip beginner-friendly.
Koh Chang, Koh Mak, and Koh Kood are close enough to combine in one week, so you can mix diving, snorkeling, cycling, and waterfall days without domestic flights.
Expect tropical water temperatures around 27°C to 30°C most of the year; many divers are comfortable in a rashguard or 3mm.
Jungle trails, viewpoints, mangroves, and waterfalls mean non-divers are not stuck on the beach, especially in the greener months.
scuba
Why Trat and Koh Chang for Scuba Diving
Koh Chang is the eastern Gulf's wreck-and-reef playground: two-tank day boats hit the HTMS Chang Wreck for big structure and schooling fish, then switch to shallower national-park reefs for coral gardens and macro life. Add Koh Mak for easy training dives and park access, or Koh Kood for quieter sites and relaxed schedules. Operators like BB Divers (Koh Chang and Koh Kood) and Koh Mak Divers make it simple to combine islands on one trip.
freedive
Why Trat and Koh Chang for Freediving
Freediving fits this island chain when you want warm water, shallow reefs, and easy boat support. On Koh Chang, BB Freedivers (BB Divers) runs freediving courses and sessions out of Bang Bao, and you can also find PADI Freediver options through local operators. Mix line training in calm-season bays with exploratory drops on shallow reefs around Koh Kood and the Koh Rang island group.
snorkel
Why Trat and Koh Chang for Snorkeling
Snorkeling is a highlight here because many reefs sit in shallow, forgiving depths, and day trips into Mu Ko Chang National Park stack coral gardens and beach stops in one outing. Koh Chang is the easiest base for organized boat trips, Koh Mak keeps it quiet and close to the park islands, and Koh Kood adds protected bays where you can snorkel when the sea is calm.
topside
What to do when you're not in the water
Between dive days you can hike to waterfalls on Koh Chang, ride bikes around Koh Mak, and chase empty beaches and river swims on Koh Kood. Expect jungle viewpoints, mangroves, fishing villages, and a relaxed food scene that is best explored one sunset at a time.
