How to fill hole in steps?

[Shpigford]

We've got an older in-ground pool (guessing put in sometime in the early 90's) and the main steps into the pool seem to be getting a little brittle.

The other day I noticed a hole about the size of a dime that I'm guessing is now leaking water, so I'm curious...what do I use to fill that hole?

I assume the steps are fiberglass and I'd say the hole is about 8-10 inches under water.

 

[Buckeyemom]

My hubby used a fiberglass repair kit in the automotive section at local hardware store - fixed the steps good - but now need to find good underwater paint for it. Anyone have suggestions for painting after the fix?