We were at a local hotel with a group of people. There were several kids running around in socks as they got in and out of the pool. I asked the parents, why the socks? They said that it cuts down on the slippery floor and also helps with the sharp pebble floor in and out of the pool. What a brilliant hack!
They sell water shoes for this purpose; waterproof slippers with grippy rubber soles that are great in a pool or on the beach. But I love hearing that regular socks could work, too.
Related: Have kids soap up at the pool shower