Boat to Thailand

I think the only boat crossing will bring you into Trat. From there you can go onwards to Koh Chang.

The only boat from Cambodia to Thailand leaves Sihanoukville at 12:00 Noon ($20, 4 hours) to Ko Kong ~12km from the border with Hat Lek in Thailand. There are no boats from Cambodia to any islands in Thailand. From Ko Kong, there will be many pickup and motorbike taxis to the border (they tend to overcharge so look out). Then deal with the border nonsense and you should see pickup and minivan rides to Trat (90 minutes) and from there transport to Laem Ngop (the port to Ko Chang). Some taxis may be able to take you directly from the border to the ferry for the last sailing. Last ferry is about ~6PM, but times vary so just get there asap if you want to go to Ko Chang. If you have to stay in Trat, there are a few hotels near the taxi huddle in the town.

Ok thank you for reply. So there are no boats to island, but are there boats to Songkhla or some other city on this coast? I would like to get to the south of Thailand.

No, the only boats from Cambodia to Thailand go from Sihanoukville to Ko Kong, near the border at Hat Lek as described. End of story. Give up dude.

No boats to Thailand except the one described by JB from S'ville to Ko Kong.