I agree with Fishinrod and 3ponds. I put cobble around my pond and some bigger stones but a random pile of slimy stones can be treacherous. It is really hard to stand up on movable stones in 2-3' of water. Even stone steps without a rail could be iffy. We employ a dock with a ladder and a shallow sloped sandy beach area. The deep part of the beach is around 3' and the slope is 15/1 (but 10/1 should be just fine) and it drops off abruptly on the deep end. We have geo-fabric and gravel under the sand. Swimmers use both but the dock allows you to keep dry. Either approach could work but I don't trust slimy rocks.

And I Love that old Otis Redding song.