Koh Kong

Pros

• Easy access via bus from Bangkok and Phnom Penh
• Cheap
• Not touristy
• "Happy"
• Good diving
• Untouched islands in nature reserve off the coast

Cons

• Not an island

Notes

• Needs more research for accommodation in beach areas
• https://www.lonelyplanet.com/thorntree/forums/asia-south-east-asia-mainland/cambodia/thailand-to-cambodia-via-koh-kong-some-advice