Christmas Point

Christmas Point is a scattered field of giant granite boulders off the northwest tip of Similan Island No. 9, known locally as Koh Bangu, sitting on a flat sandy bottom. Divers typically enter on the outer side and work down through boulders weathered into distinctive scooped shapes before reaching the dive's centrepiece: a swim-through arch at 18-24 m, large enough to be the reason most operators run this site. Several smaller swim-throughs branch off it for divers who want to keep exploring before moving on. Past the arch, the route continues to a boulder ridge in the deeper, outer part of the site, a reliable spot to find zebra sharks and reef sharks resting on the sand in the morning. Heading back toward the island, the boulders close up and the water shallows into a coral-fringed edge where table corals shelter smaller reef fish, and it's worth a last look at the blue for a passing manta or other pelagic before the safety stop.

The draw here is the maze itself: a stack of boulders large enough to break the surface, laced with one signature arch and several lesser swim-throughs, on a site large enough that operators describe it as worth diving more than once. A 2009 post from a diver with extensive local experience named Christmas Point among the Similans' six best dive sites, first on the list heading north to south, which at minimum says the site holds its own against better-known names in the archipelago. In the years after a regional coral-bleaching event, divers reported the reef here as one of the ones that came through in good shape, alongside a handful of other Similan sites. The manta ray and occasional whale shark that turn up here are a genuine bonus, corroborated across several operators, but they pass through; they don't live here, and the topography is what a diver actually comes for.

The current is the site's main variable: moderate to strong, it changes direction with the tide, and a full moon can push it hard enough to carry divers toward the deeper part of the site if they drift off the boulders. Stay close to the rock when it picks up and keep an SMB on hand. The outer boulder base and drop-off run to 35-40 m, well past Advanced Open Water's ceiling, so the deeper half of the site calls for Deep Diver training or solid depth experience; the shallower 8-25 m band, including the arch, stays within recreational limits. Descent method varies by day and by operator, since a mooring buoy isn't always in place, so get the plan from your guide's briefing and don't assume a line will be there. A camera earns its place in the boulder maze; some divers also bring a torch for peering into the crevices and overhangs along the way.