Best Thai Islands for Snorkelling: Visibility, Marine Life & How to Get There

Thailand's clear Andaman Sea and Gulf of Thailand waters offer world-class snorkelling, with the best experiences often accessible directly from shore or on short boat trips. The top islands for snorkelling: Koh Tao (Gulf) — the standout for marine life density; visibility regularly reaches 20–30m, and you can see whale sharks during the right season (March–April), plus abundant reef fish, turtles, and sea horses. Koh Lipe (Andaman) — consistently rated among Southeast Asia's finest snorkelling; pristine coral gardens just metres from the beach, extraordinary fish variety, and outstanding water clarity. Similan Islands (Andaman, day trip from Khao Lak) — a national marine park with some of Thailand's healthiest coral reefs, massive boulders, and outstanding diversity. Koh Phi Phi (Andaman) — the famous Phi Phi Lee lagoon and Viking Cave bay offer excellent snorkelling, though crowds have increased. Koh Surin (Andaman) — remote national park islands with pristine shallow reefs and regular manta ray sightings. Best season for Andaman: November–April (calm, clear). Best for Gulf: April–October. Budget for equipment rental: ฿100–200 per day. Bring reef-safe sunscreen and avoid touching corals.