I've seen this spelled Cheow Larn Lake and maybe something else... I assume translating from Thai to English can be a little tricky.
Anyway, this is just on the north side of Khao Sok NP and is the coolest lake I've ever seen. The turquoise water reflecting the mountains and those awesome rock formations make for a dramatic view, and taking it all in from a floating cabin finishes off the mood nicely.
When we left, our guide said happy birthday to Anna and gave her a cake! We were really confused since Anna's birthday wasn't for another six months, but the cake looked good so we just said thanks and went with it. Later, as we were waiting at an overlook for our next ride to show up to take us away, one of the drivers who brought us to the overlook got a phone call and came over to ask "is it your birthday?" When we said no, he apologized and took the cake back. I guess it was meant for someone else.