Thanks to everyone for all of the excellent advice. I have purchased four more data cards so I now have one per day. I'm not going to stress about backing them up in the field. I have bought a wallet to keep them in and have a system for telling empty from used. The silica gel idea is great. I bought a bag of unscented silica gel kitty litter and some stockings to make as many sachets as I need. And I've decided to take along my half dead old camera body just in case there's a tragedy with my new camera. Thanks again all. I hope to come back with some great images and memories.