It's actually a lot of fun to test gear this way. Get in the water with it and see how it performs. Just don't put anything important inside while you're testing!
So here goes. Testing the WildWasser in a lake.
I punished it a bit by trying to force it underwater in numerous ways.
By hand. This was tough. With one hand, I had a lot of trouble forcing it completely underwater. It fought me to stay on top of the water.
I've taken my big blue WildWasser Kayak Deck Bag kayak camping with me in the 1000 Islands near Gananoque, Ontario and attached it to the front deck of my Boreal Baffin. It gave me lots of extra storage space, and under moderate use, like kayaking with wind and waves, it did keep everything dry inside. Although, I only trust my cell phone, car keys, and wallet inside any dry bag if it is in something I know is completely watertight, like a trusty Pelican hard case. Why take a chance?
Lots of kayak deck bags on the market have a lower, flatter profile. It's true. My blue WildWasser Kayak Deck Bag is a bit round and has a fairly high profile, so you have to paddle a little higher to clear it if you carry it on the front deck of your kayak. But, it is very roomy inside and so well outfitted for attaching it to your kayak, carrying it on shore, and attaching things to it, that I can't complain.
Paddlers are always asking for a fully waterproof deck bag. Some leak badly. Can you fully submerge yours without some water leakage?
WildWasser Kayak Deck Bag. Pass or Fail?
Are you testing your gear? Are you happy you did?