I won't tell you the whole story of one of my great times on a lake shore as you can read it in my book but I wanted to make sure you don't miss any opportunity to enjoy the cool water of a lake and the sun on your skin to have some amazing sex.
Again: always stay safe.
A fun thing to do is to swim close to some fishermen who will complai you are too close, excuse yourself and get out of the water, fully naked, letting them see you ... If they aren't too timid this may create a nice moment!
Or just lying in the sun and letting your man/woman touch you ... And more.
It can even be hotter with some cuffs and a tree ....