Booked 2 fun dives with The Dive Shop in Sihanoukville (note that tragically their main office on Serendipity Beach Rd was burnt to the ground along with Monkey Republic afew weeks ago, so they have a temporary office on the same road about 30m further back towards the beach in a restaurant, look for the sign on the footpath)
Professional and courteous from the start, the owner Dennis provided comprehensive information about the day's activities. Note that its quite a long day - 25 minute tuktuk to the port, 2 hour boat ride to Koh Rong, gear up, 30 mins to dive site (approx), back to Koh Rong for lunch, back out for 2nd dive and then 2 hour journey back. The wonderous scenery and breaktaking sunset on the way back made every minute worthwhile. Theres also the alternative to go out and stay on the island overnight if you have the time.
The team were very safety conscious, really detailed briefing and small group numbers. All the gear was in very good condition. Its worth commenting that whilst I was there in April, the visilbility was very poor (3-5m) so its quite difficult to see much, but theres some interesting micro-life & nudibranches that make the dives worthwhile.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.