Those knives rust very easily. Mine rusted and I've never taken it in water ever. I live on a small Island things rust very easily. You should get something waterproof like a bag of case
http://www.inventivesolutions.net/itmidx1.htm
or
http://www.pelican.com/main.htm
Oil it before and after even if you use WD 40 it's better than nothing.
Hope this helps.

Frank