Getting to and from Cambodia's islands, can be quick and easy, or maybe not?

Several speedboats running between Koh Rong Island, SihanoukVille, and Koh Rong Samloem, can carry up to 140 people, and cost $20 round trip.  Between Sihanoukville and these two islands, the trip takes 45 minutes; between the two islands it's about 10 minutes.  Figure 1 hour mainland to island.  Koh Rong and Koh Rong Samloem are generally 2 hours from SihanoukVille by slow boat, and costs $10 for the round trip. 

Rides can take 2 minutes to the closest island (a trip on the bridge to Snake island takes about 2 minutes), to an 8 hour ride on a small boat to the farthest island.

Koh Thmei and Koh Ta Kiev Island are the only other islands with daily trips.

All of the helicopter services to the island are headquartered in Phnom Penh  Song Saa Island has a sea plane to take customers to the islands from Siem Reap (Angkor Wat)

Koh Ta Kiev Island is about 1 hour boat ride from Otres Beach, and costs about $20 for the round trip.  It's about 15 minutes from Ream National Park.

Once you're on an island, your feet do the walking.  Some larger islands have bicycles for rent.  You can also rent a boat to go island hopping or fishing, starting at $10 for the whole boat and captain for a short trip.

Most bungalows on the islands rent kayaks for day trips, and the price varies from $2/hour and up.