Where to Dive in Thailand: Best Time, Month by Month
Where to dive in Thailand and the best time to go: Andaman vs Gulf monsoons, when the marine parks close, and diving near Bangkok in Pattaya and Sattahip.
Where to dive in Thailand depends first on when you go. Thailand has two coasts, the Andaman Sea and the Gulf of Thailand, and their monsoons come at different times. Several marine national parks close completely for the monsoon. This guide covers every area in our dive season chart: when each one is at its best, when it is closed, and where to dive near Bangkok.
Seasons and closures come from Thailand's Department of National Parks, Wildlife and Plant Conservation (DNP), the Thai Meteorological Department (TMD) and the Tourism Authority of Thailand (TAT). We last checked them in October 2026. Park dates can change from year to year, so always check the park's latest announcement before you travel.
Andaman vs Gulf: different good months
- Andaman coast: the southwest monsoon arrives from about mid-May to mid-October, with heavy rain and rough seas peaking in September, so several marine national parks close for it.
- Gulf of Thailand: the southern Gulf gets the northeast monsoon from mid-October, with heavy rain into December and the most in November. During the southwest monsoon it stays drier than the Andaman side.
The monsoon data is from the TMD. In practice: during the southwest monsoon, when several Andaman parks are closed, the Gulf is drier and Koh Tao is in its June to September good months. When the Gulf turns wet, the Similan Islands reopen after 14 October.
Andaman: Similan, Surin, Lanta, Phi Phi, Phuket
- Similan Islands: closed every year from 16 May to 14 October, because monsoon seas are unsafe and the reefs get a rest (according to the DNP). Our chart marks November to April as the best months (according to TAT).
- Surin Islands: closed for the monsoon from 16 May. The park gives mid-May to mid-October as its rainy season and names the hot season, mid-February to mid-May, as the best time to go (according to the DNP). Check the park's reopening notice before you go.
- Koh Tachai: closed for reef recovery since 15 May 2016, with no reopening date announced yet (according to the DNP).
- Koh Lanta / Hin Daeng-Hin Muang: Hin Daeng, Hin Muang and Koh Rok close every year from 16 May to 15 November because of monsoon seas (according to the DNP), so our chart counts December to April as the best months.
- Phi Phi / Phuket: no area-wide closure, but the monsoon brings heavy rain and rough seas. Our chart marks December to April as the best months (according to TAT). In 2026 Maya Bay was closed from 1 August to 30 September (DNP announcement).
Gulf of Thailand: Koh Tao, Koh Phangan, Chumphon
- Koh Tao: best from February to April and June to September (according to TAT and the TMD). October to December brings heavy northeast-monsoon rain.
- Koh Phangan / Sail Rock: driest around February and wettest around November, with the northeast monsoon. Our chart marks February to April as the best months.
- Chumphon: gets both monsoons; the gap between them is the hot season, February to April.
Diving near Bangkok: Pattaya, Sattahip, Samae San
If you want to dive without flying far, people often search for Samae San and Sattahip. Our chart groups this area as Pattaya / Sattahip (we count Samae San within the Sattahip area).
- Rainy from mid-May to mid-October, wettest in August and September (according to the TMD).
- Our chart marks November to April as the best months.
Best time to dive in Thailand: every area at a glance
| Area | Coast | Best months in our chart | Park closed / heavy rain, rough seas |
|---|---|---|---|
| Similan Islands | Andaman | Nov–Apr | Closed 16 May–14 Oct |
| Surin Islands | Andaman | Feb–Apr | Closed from 16 May (check reopening notice) |
| Koh Tachai | Andaman | None | Closed for recovery since 15 May 2016 |
| Koh Lanta / Hin Daeng-Hin Muang | Andaman | Dec–Apr | Closed 16 May–15 Nov |
| Phi Phi / Phuket | Andaman | Dec–Apr | Rough seas, heavy rain May–Oct |
| Koh Tao | Gulf | Feb–Apr and Jun–Sep | Heavy rain Oct–Dec |
| Koh Phangan / Sail Rock | Gulf | Feb–Apr | Heavy rain Oct–Dec |
| Chumphon | Gulf | Feb–Apr | Heavy rain Oct–Dec |
| Pattaya / Sattahip | Gulf | Nov–Apr | Wettest Aug–Sep |
See it month by month, in colour, in our dive season chart.
Other places people search for
People in Thailand also search for diving at Koh Chang, Koh Kood, Koh Larn and Krabi. These are not in our season chart yet, because we have not checked them against official sources. If you are interested, ask us on LINE first.
Planning a dive trip
- Pick the coast by month: check our dive season chart to see which coast is in its good months when you are free.
- Check the park announcement: marine park closing and opening dates can change every year. Read the DNP's latest announcement before you book a boat or a room.
- Check the tides: the Royal Thai Navy Hydrographic Department publishes tide tables with predicted tide heights hour by hour, for every day of the year, with stations on both the Gulf and Andaman coasts. Use them to plan dives; for navigation, use the Hydrographic Department's official publications.
- Not certified yet: start with learning to dive: Open Water.
- Sort out your gear: see what you need and what you can rent in our scuba gear list.
Dive trips with us
No trip dates are announced yet. Tell us on LINE @diverecords where you would like to dive, when you are free and whether you are certified yet, and we will reply in the chat with the nearest dates. Open trips appear on our dive trips page.
- Booking requires a 30% deposit; the balance is due at least 7 days before the trip.
- If you cancel, the deposit is not refunded, but you can reschedule once with at least 3 days' notice.
- If we cancel for weather or safety reasons, you choose a new date or a full refund.
The full terms are on our shipping and returns page.
FAQ
Where can I dive near Bangkok?
In our chart, the area near Bangkok is Pattaya / Sattahip, which includes Samae San. It is rainy from mid-May to mid-October, wettest in August and September. Our chart marks November to April as the best months.
When is the best time to dive Koh Tao?
February to April and June to September. October to December brings heavy rain from the northeast monsoon.
When are the Similan Islands open?
The Similan Islands close every year from 16 May to 14 October. Our chart marks November to April as the best months. Dates can change, so check the park's announcement before you go.
Where can I dive from October to December?
In these months the southern Gulf gets the northeast monsoon, while the Andaman parks reopen: the Similans after 14 October and Hin Daeng-Hin Muang after 15 November, unless the park announces a change.