What is the best DIY to hang beach towels poolside?

You could have weighted your pvc with sand in the tubes

I've put small hanging hooks on the back wall of my house and I did them at different heights and hang colorful beach towels from them. Really cute idea, now all my friends have done it too!

did you like the pvc coat stand for the look? If you did, can you anchor it into the ground or deck so that it stays upright?

Big decorative hooks attached to a long board then attached to a wall.

I was thinking something like a cross between an over-the-door rack and a sandwich board like out front of a bistro. You have the sandwich board that connects two boards at a hinge at the top, and it spreads out at the bottom to keep it upright. You can get heavy wood or composite material to make the sandwich board, and then you can cut holes to hang the towels. And you can do this on both sides.

You can even paint these boards some nifty design that goes with the pool decor or has water themes or such. Happy swimming!

How about 3/4 pvc TOWEL RACKS screw to the fence, which will help with drying.

Instead of the coat rack look, you could do the one below. But FILL the bottom piece with sand first to weigh it down and make it wind proof. If you really liked your coat stand look instead, take apart on bottom, and add sand to weigh it down.