Industrial size available in some sporting goods stores or online for bear protection in giant canisters - you can clip it onto your belt or stuff it in your pocket.
TX LOCAL: BIG BEND FATALITY
http://www.nps.gov/bibe/pressreleases/visitorfatality_052404.htm
Good reason why WATER should be number one on the survival list. This guy went hiking and died within ONE DAY due to dehydration. Death is very very close without water.