Thai Diving Season & Visibility Calculator
Visibility, water temperature, current, and certification per dive site.
What this solves
Thailand has world-class diving split between the Gulf of Thailand (Koh Tao, beginner-friendly) and the Andaman Sea (Similan, Richelieu Rock, advanced). Each site has different peak seasons and visibility. Whale sharks appear in Richelieu Rock February–April. This calculator matches site + month to visibility, temperature, and certification requirement.
How to read results
Visibility is in meters — higher means better. Water temperature affects whether you need a 3mm or 5mm wetsuit. Current strength tells you if it's suitable for beginners. Certification requirement is the minimum PADI/SSI level needed.
Limitations
- Conditions are averages; specific days can vary widely.
- Similan closes mid-October to mid-November — verify before booking.
- Richelieu Rock is a liveaboard-only site, often rough.
FAQ
Where can I learn to dive?
Koh Tao is the world's most popular place to get Open Water certified. 3–4 day courses cost 8,000–12,000 baht. Over 50 dive shops operate on the island.
When can I see whale sharks?
Richelieu Rock peak: February to April. Similan: also February to April. Whale sharks are wild animals — sightings are never guaranteed but the probability is high in these months.
Is diving in monsoon safe?
Some sites close entirely (Similan). Others stay open but visibility drops and currents strengthen. Liveaboard trips continue year-round but require experienced divers.
Sources
- PADI — published Thai dive site seasonal information.
- Department of National Parks — Similan closure calendar.
- Phuket Marine Office — published whale-shark sighting reports.