Richelieu Rock’s cloak of hot pink, steamy red, and royal purple coral and relentless flurries of fish stole my heart. In the Andaman Sea and regarded as Thailand’s premier dive site, this flat, horseshoe-shaped limestone rock delivered a memorable dive … and the award-winning photo that appears below and on my home page.

Forty nautical miles to the south are the Similan Islands, nine granite boulder islands with multiple dive sites.