Racha Noi Bay, Thailand: Reef and Sand Slopes

Racha Noi Bay sits on the southeast side of Racha Noi island, defined by a distinct small islet. During low tide, a sand ridge visibly connects this islet to the main landmass. Your dive here typically starts in the shallower waters of the bay, circumnavigating this small island. The topography shifts from fine sand to vibrant coral, then to granite formations both above and below the surface, providing a varied underwater landscape.

The shallow areas, particularly the coral gardens to the north and south, start at approximately 5 to 10 metres. Here, you'll find healthy branched coral formations before the bottom transitions into a pure white sand slope around 12 metres. This sandy expanse extends deeper, creating a habitat for species that prefer these open substrate environments. Keep an eye out for garden eels (Heteroconger hassi) and stingrays (Dasyatis pastinaca) camouflaged against the white sand.

As you move around the small islet, the environment transforms. The soft corals give way to dynamic rock formations with large, stacked granite boulders. These crevices and overhangs offer shelter to various reef inhabitants. Giant moray eels (Gymnothorax javanicus) and puffed-head pufferfish (Sphoeroides testudineus) are commonly seen in these rocky areas, using the structure for cover.

Below 30 metres, the deeper rocky sections host gorgonian fans and sea whips, creating a different kind of underwater scenery. This vertical structure attracts a different suite of marine life. While the primary focus might be the reef, the chance of encounters with larger pelagic species offshore is a draw of Racha Noi Bay.

Visibility here is generally good, often reaching 20 metres or more. However, some days it can sit between 10-15 metres, depending on conditions and time of year. Currents are typically weak to moderate, though areas around the small islet can experience a gentle current. These shifts in current can sometimes bring in pelagic visitors.

The bay's mix of hard coral structures, sandy slopes, and granite outcrops supports a diverse fauna. You will find globe fish (Tetraodon), sea cucumbers (Holothuroida), nudibranchs (Nudibranchia), octopuses (Octopoda), and cuttlefish (Sepia). Specific reef fish like sweetlips (Plectorhinchus) and angelfish (Pomacanthidae) are common. Look for scorpionfish (Scorpaenidae) well-camouflaged on the rocks.

Racha Noi Bay also offers opportunities for encounters with larger marine life, especially when a gentle current moves through. Eagle rays (Aetobatus narinari) are regularly sighted, often gliding gracefully over the sandy areas or near the rocky structures. There's also the possibility of spotting leopard sharks (Stegostoma tigrinum) resting on the sand, or the distinctive milkfish (Chanos chanos) in open water.