The
Speed Ferry ($ 20 open return if you book from an agent in Sihanoukville)
leaves the mainland at 09:00, 11:00 and 15:00 and stops first at Saracen Bay (45 minutes), then Eco Sea Dive Centre and then M'Pay Bei — all on Koh Rong Samloem — before heading over to Koh Touch beach on Koh Rong.