I wouldn't go deep sea diving with one, but they are certainly water resistant enough to be worn in the pools, at the water parks and on Splash Mt. or Kali River Rapids.
We wore them at Typhoon Lagoon. Went in the snorkel pool, on most of the slides and stayed in the lazy river for a long time. We had a credit card linked to them. It was so much easier not having to carry anything or leave anything on a chair there or rent a locker.
Being able to swim with them is one of my favorite parts!!! Food stops while on the lazy rivers at the water parks!!! Greatest thing ever!!! #icecreamsundaesTyphoonLagoon #eatmoreswimless
They are spec'd to a depth of either 20 meters or 20 feet. I would have to dig up which it is, but even the smaller depth will get you to the bottom of most places we are likely to be at WDW.