Two coasts, opposite weather
The Gulf is at its best: calm water, sunny mornings, good visibility for diving. The Andaman is in the middle of the monsoon, with rough seas and frequent afternoon rain.
Holidays and crowds
12 August is Mother's Day and a long weekend, when Thai families travel — book accommodation ahead for that week. Otherwise August is quiet.
What to do
Dive or snorkel around Koh Tao, take a boat to Ang Thong, or head north for the hills, which are green and cool. Skip island-hopping on the Andaman.
