I bought this for reading in the bath, but I can see it would be good for taking your Kindle to the beach or other "danger areas". I had expected a zip lock, but it has a double-roll closure similar to that used in canoe bags - lo-tech but very effective - and a velcro'd flap as well. The back is very slightly padded and the plastic is stiff, so it's quite sturdy. It also comes with a little zipped bag, so the case itself won't get scuffed in transit.
Downside - it has TRENDY DIGITAL emblazoned across it!
Handy hint: put the Kindle in upside down, so that if it switches itself off you don't have to take the whole thing out to turn it back on, just open the case.