If you are traveling from/to Thailand, it makes sense to spend at least one day and night in Koh Kong. Koh Kong has the best zoo (to me) in Cambodia and even beats the Sracha tiger zoo.
There are the usual zoo sight seeing things, along with some interesting live shows. There is the man that puts his head inside an alligator’s head.
Next there is a bird show where the birds do math and perform flying stunts.
Also, there is a tiger show with about 7 tigers jumping through fire and doing tricks.
My favorite at the Koh Kong Safari Zoo was the orangutan show. They do a comedy skit with the orangutans getting ready for a boxing match, and then the orangutans actually box!
At the end you can take a picture with the orangutan for a small donation, i’d suggest a dollar.
Link for the Koh Kong Safari Tiger Zoo is Here. Price is 12 dollars for foreigners and 10 for Khmers (or if you have an id or possibly a work id from Cambodia.)
The location if coming from the Cambodia side will be after the long bridge where you pay a toll. The toll is I believe 1000 riel for motobike (more for car) and will be included in the tuk tuk or motodops price. After crossing the bridge continue to go right when it elbows at a statue…Go for another minute or two and turn left. There will be a small sign. Continue past the nice ocean side beach huts and continue for another minute where you take a small left and are at the Koh Kong Safari Zoo now.