Andaman Scuba

Andaman Scuba has been diving out of Khao Lak since 1997, which makes it one of the town's original operators, and it still runs the full Similan menu from its base on Bang Niang Beach, including day trips, courses from first breaths to professional level, and multi-day liveaboards on its own boat, Bunmee IV. The routes are the ones that make Khao Lak worth the trip in the first place. The Similan and Surin islands, Koh Bon, Koh Tachai and Richelieu Rock, the pinnacle I'd build an entire Thailand dive trip around.

What I'd single it out for is scale. This is a small-group shop rather than a fleet, and the reviews keep coming back to the same things, namely the crew, the food on board and the feeling of being looked after by people who have clearly been doing this a long time. When the Similan park closes for the monsoon, the operation moves its liveaboards south to the Phuket side for Koh Haa, Phi Phi and the Hin Daeng and Hin Muang pinnacles, so there is a boat to book in most months.