Koh Samui sits in the Gulf of Thailand, and its underwater world is a compelling reason to visit. Clear water, colorful reefs, and year-round diving conditions make Samui one of the most accessible entry points for diving and snorkeling in Thailand.

Best Season for Diving

Conditions vary by season. February through October brings calm seas, 15–20 meter visibility, and water temperatures of 28–30 °C. November and December mark the rainy season on the east coast — waves pick up and visibility drops. During this period, diving trips relocate to the western shore or to neighboring Koh Tao and Koh Phangan, which enjoy calmer weather at that time.

Top Dive Sites

Most popular dive sites are located beyond Samui itself — in the Ang Thong National Marine Park and around Koh Tao. The highlights:

  • Sail Rock — a vertical pinnacle between Samui and Koh Tao, descending to 40 meters. A magnet for whale sharks (season: February–May). Recommended for experienced divers.
  • Chumphon Pinnacle — rocky formations with rich marine life: tuna, hammerhead sharks, and rays. Depth up to 36 meters.
  • Koh Tao — the closest diving island to Samui, with dozens of sites for all levels: shallow reefs for beginners and deeper zones for advanced divers.
  • Shark Island — a rocky outcrop off Koh Tao with blacktip reef sharks, octopuses, sea turtles, and large reef fish.

Snorkeling on Samui

Snorkeling is possible at several spots directly off the island's shores. The northern tip — Choeng Mon bay — is relatively calm with small reef patches. Excellent snorkeling is available in Ang Thong National Marine Park: crystal-clear shallow water and abundant tropical fish, accessible via day-trip boats from Samui.

Dive Training

Certified dive centers operate on both Samui and Koh Tao, offering PADI and SSI courses. For beginners:

  • Discover Scuba Diving — a one-day introductory dive with an instructor, no certification required. Perfect for first-timers.
  • Open Water Diver — a 3–4 day certification course granting an internationally recognized dive card valid to 18 meters.
  • Advanced Open Water — the next step for certified divers looking to go deeper and explore specialties.

Russian-speaking instructors are available at several schools — confirm when booking. Most dive centers offer full packages including transfers, equipment, and meals on board.

Equipment

All gear — masks, fins, regulators, tanks — is provided by dive centers as part of the package. If you plan to dive frequently, bringing your own mask is worthwhile: rental masks are fitted to a generic standard, while a personal mask fits far better.