Look at fire resistant lockable storage box/fire safe. You can find these at Home Depot, Lowe's and most likely Sears. They run around $20-50 depending upon the size and features you might want. They are generally watertight and will provide approx. 3 hours of heat protection. Pete

Here are some examples:

http://www.lowes.com/lkn?action=productDetail&productId=50401-254-1100

http://www.lowes.com/lkn?action=productDetail&productId=49770-254-1170

http://www.lowes.com/lkn?action=productDetail&productId=50056-254-S0310