Hat Lek is the location of the southern-most border crossing between Thailand and Cambodia, its counterpart on the Cambodian side being Koh Kong.

Get In

From Bangkok

Take one of the many regular buses to Trat from either the Eastern Bus Terminal (Ekamai) or the Northern Bus Terminal (Moh Chit). Direct 1st class buses from Ekamai average a bit more than 5 hours, the less frequent frequent services from Moh Chit take a little less. While most 2nd class buses take a lot longer as they make more stops and use slower and less direct routes, the midnight departure from Ekamai takes only 4.5 hours.

From Trat, take a minibus direct to the Hat Lek border crossing - departures every 45 minutes between 06:00 and 18:00, takes between 1.5 and 2 hours, 110 baht.

Do

Cross the border and enjoy Cambodia but be aware that the border opens at 07:00 and closes at 20:00. If you want to go on directly to Sihanoukville by sea, keep in mind that the boat is scheduled to leave at 08:00 (in practice it often leaves a little late - typically around 08:20).

Extracted from Wikipedia: Hat Lek