To avoid any confusion from the start, Richelieu Rock is next to the Surin Islands National Marine Park and NOT part of the Similan Islands. Its connection with the Similans is mainly due to the fact that many divers like to dive Richelieu Rock during a Similan liveaboard trip. Surin and Richelieu Rock are quite a distance north from the Similans, and the time to travel from one to the other depends on the type of boat and the sea conditions.

Richelieu Rock is regarded as one of the best dive sites in the world and THE BEST that Thailand has to offer. Why is this so? Well, the main factors are that being far out into the Andaman Sea and standing alone, Richelieu Rock attracts large pelagic (open sea) fish which often include whale sharks and manta rays, as well as having wonderfully clear waters and good marine life at shallower depths, due to hard and soft corals which are in good condition. One just needs to do a little research in to the top dive sites listed by a certain Jacques Cousteau. Divers visiting Richelieu Rock must be aware that sightings of whale sharks are by no means guaranteed. However, while they're waiting, or missing out, there are plenty of other wonderful creatures to observe at all depths. The best diving there is seasonal, with November to April being the best. In addition, rough seas and the occasional introduction of new regulations by the Thai government can prevent access to the remote pinnacle that is Richelieu Rock.

Not far from Richelieu Rock (15km west – away from the mainland) and just 7km from the Burmese border are the two Surin Islands. Here the shallow-water coral life is extremely healthy and diverse and, with very few tourists, can offer remarkably natural and enjoyable snorkeling and diving. Lots of turtles can be seen (even when snorkeling) as well as the huge and interesting Napoleon Wrasse and Bumphead Parrotfish. Divers should also be prepared for the possibility of seeing grey reef sharks at depths of about 30 metres.

Visiting Surin National Park and Richelieu Rock is a must for those who want to know that they have experienced the best diving in one of the world's best diving countries. At present, the logistic challenges of travel keep Richelieu Rock and Surin Islands from over development as well as offering non-divers the opportunities to catch a glimpse of what's under the crystal clear waters on the Andaman Sea.