Racha Noi is the more isolated of the two islands and is a popular dive-site for more experienced divers, as the depths are generally greater and the currents frequently stronger than at its sister island to the North.
You will encounter huge underwater boulders that offer a good chance to see manta rays and whale sharks. The northern tip of the island offers an opportunity for a good multilevel dive along a large pinnacle where spotting larger marine life like Reef Sharks and Stingrays is common.
Off the southern point is a nice drift dive along some spectacular scenery as you find yourself on top of a large rock formation surrounded by deep water. On the southwest side there is a wooden ship-wreck that draws a lot of interesting reef fish. Racha Noi offers many opportunities for an enjoyable and rewarding deep-dive but due to the potential for strong currents here many of the dive shops will only bring divers here who have an advanced certification.