I work in a job that has me moving a lot and I've had a lot basements that get flooded. I would suggest that you block the safe up off of the floor and get a dehumidifier down there. They're pretty cheap and work well. I would also suggest that you pipe it to a drain if you can. The bucket that comes with these will fill up pretty quickly and if you don't empty it oftenyou might as well not have one.

Good luck.