Once over the mountain pass from the winding Phnom 1500 road you will reach Thma Da Waterfall.
This is a multi-level waterfall with a surprising number of visitors considering its remote location. At the site, you will find the usual Khmer food vendors and wooden huts with hammocks to relax and picnic.
The waterfall itself drops down to a lower level. This is pretty much inaccessible except for the super-adventurous via a precarious rope hanging over the edge. In the dry season there are pools of water to take a dip and refresh, but not any deep pools suitable enough for proper swimming.