I bought one of their survival whistles (at least, I think it was one of theirs - it looks identical to the one in the photograph) and stuffed a cotton ball inside the secret compartment. Then I dropped it in a coffee cup full of tap water and left it there overnight. When I shook it off and opened it the next day, the cotton was as dry as when it went in. With that, and the key-flint and SAK on my keychain, I would have no worries about starting a fire, even after a severe dunking in the river. (The key-flint is an idea I got from this forum - I crazy-glued 4 Coghlan's lighter flints to a key blank and carry it on my keychain, along with a SAK Classic.)