I know this seems like a crazy idea but hear me out. While I have a Time Machine back up hard drive, I'd like to have an 'off-site' back up hard drive. So I was thinking of getting an external HD putting is some sort of durable case (thinking a Pelican case), put it underground in my yard. This way my data is safe in the event of a fire or burglary. It would be updated once a month or so. A problem though: condensation. Would a Pelican case (which would probably be put into a box or something itself) seal out moisture? Would getting those silica gel packs and putting them in the case help? I know there's "cloud" solutions, but I'm still curious about this idea. Any insights?