The ocean will take your pool float. The lake won't.

Pool floats are lake and pool toys. They are not ocean toys.

The ocean has wind, current, and tide. All three push a float faster than you think, and there is no anchor that will hold you in place on a sandy, sloping ocean floor. You will drift, and drifting in open water is how people end up needing a rescue. Even near shore, a light offshore breeze can pull you out faster than you can swim back. If you want to float in the ocean, use a proper ocean-rated float or just body-surf. Don’t use the inflatable unicorn.

For a lake, anchoring is easy. You don’t need a fancy boat anchor — a cloth or nylon sandbag anchor filled with sand works great, or a small 5-10 lb mushroom anchor if you want something more permanent. Tie it to a length of rope, drop it over the side, and let it settle. Give yourself a little slack and you’re set. If you’re cheap (like me), a plastic milk crate filled with rocks does the exact same job for zero dollars. Just make sure the rope is long enough for the depth you’re in, and test the pull before you all climb on.

Lakes get waves too, but they don’t have current pushing you sideways the whole time. That’s the difference.

One tip: whatever anchor you use, tie the rope to the float’s handle, not the inflation valve. Learned that one the hard way.