Half the pleasure of the Cambodian coast is that it takes just enough effort to reach. Nothing here is hard to get to, but the islands still sit at the end of a boat ride, which keeps them feeling like somewhere you have travelled to rather than simply arrived at.
To the south
Most coast trips start from Phnom Penh. From the capital you can fly, drive or take the revived railway south to Sihanoukville, the main jumping-off point, in a few hours. The road also carries on to Kampot and Kep, the gentler mainland coast, through green country and pepper hills. Sihanoukville has its own airport too, with a growing handful of regional flights, so some travellers skip the capital entirely.
Out to the islands
From Sihanoukville, fast boats run several times a day to Koh Rong and Koh Rong Sanloem, taking anywhere from forty minutes to an hour depending on the boat and the swell. Tickets are easy to arrange, and the crossing itself, out across the turquoise into a widening blue, is the moment the mainland and its noise fall away. Smaller boats reach the quieter islands, and down in Kep a short hop carries you to Rabbit Island.
The rhythm of the boats
The one thing to respect is that boats run on weather and season. In the calm dry months they are frequent and reliable; in the green season they run less often and occasionally not at all. Build a little slack into your plans, especially around a flight home, and treat a delayed crossing as part of the texture rather than a problem.
How to be here
Fly or train to the coast, buy your boat ticket the day before, travel light and waterproof, and give yourself a spare day at the end. The journey out is short, lovely, and the proper threshold to island time.