Scuba Diving in Koh Tao

Good to Know

• Sail Rock is the one site that genuinely requires a long transfer (over an hour each way) and is normally sold as a dedicated full-day, two-dive trip rather than a quick add-on — factor in a full day if you want to dive it.
• Conditions are directional: the two monsoons (northeast, roughly Nov–Jan, and southwest, roughly May–Sept) each hammer a different side of the island, so dive centers simply switch to whichever coast is sheltered that week — expect your operator to substitute sites rather than cancel outright.
• Whale shark odds are seasonal and never guaranteed, but divers and operators most often report sightings around March–May and September–October at the offshore pinnacles and Sail Rock.
• If you're chasing the clearest water rather than the calmest seas, several experienced local instructors rate September–October (just before the monsoon sets in) as delivering the best visibility of the whole year, sometimes 40 m+, even though it's technically shoulder season.
• Koh Tao is one of the highest-volume places in the world to get an entry-level scuba certification, and heavy competition between shops keeps Open Water course prices well below equivalents in many other countries.
• Advertised 'from' prices often exclude eLearning materials, certification card fees, or gear surcharges — always ask for the total all-in price before booking, since bundling varies a lot shop to shop.
• If you plan to do a Divemaster or Instructor internship, factor in that PADI's own professional-level exam/certification fees are typically billed separately in AUD and are on top of the shop's course fee.
• SSI has an unusually large foothold on Koh Tao compared to most dive destinations, so it's worth deciding whether you want a PADI or SSI card before choosing a shop, since it affects which agency's card and later teaching options you'll have.
• If freediving interests you, look specifically for a shop or school with a named freediving-specific certification (AIDA, PADI Freediver, SSI, Apnea Total, Molchanovs) rather than assuming any scuba shop teaches it — it's common but not universal here.