Ko Racha Yai

Ko Racha Yai, sometimes Raya, lies about twenty kilometres south of Phuket and is known for visibility - the water around it is among the clearest close to Phuket, which made it the standard site for dive training and introductory dives out of Chalong. Ao Bungalow and Ao Siam are the main bays, with white sand and shallow reef straight off the beach. The reef is the honest problem: severe bleaching events, particularly in 2010 and again in later years, killed a large proportion of the coral here, and the Department of National Parks closed sites around Racha for recovery periods. What remains is patchy, with recovery slow and further bleaching a recurring risk as sea temperatures rise. Day trips arrive from mid-morning and the bays are busy until mid-afternoon. There is limited accommodation and staying overnight gives quiet water. Crossings are rough or cancelled in the monsoon.

The landscape

• The visibility - among the clearest water near Phuket, hence the dive training.
• The shallow reef - straight off the beach in the main bays.
• The bleaching damage - substantial coral loss and closures for recovery.
• The day-trip rhythm - busy from mid-morning, quiet overnight.

When to go

November to April; crossings are rough or cancelled from May to October. Early or late in the day avoids the day-trip boats.

Things to know

Coral has been heavily bleached and is much reduced from what photographs and marketing suggest; some sites close for recovery. Very busy midday with speedboats. Limited accommodation and facilities.

Nearby

Ko Racha Noi is further south; Phuket and Chalong pier are north.

Key facts