They don't have any kind of seal around the lid, so they're not "waterproof" in terms of being submersible, but they don't get rain in them, and are perfectly waterproof up to their tops. I've organized my entire storage and garage with these, but again, only if you can get them at Costco prices. They're sturdy and stackable as well, interlocking between bases and lids very well.
Snugpak bags. Reasonably water resistant unless you are a white water guy who flips his boat a lot. Good variety of sizes to from 1 litre to 70 litres.