How am I suppose to shave my armpits and legs?

I have very dark and thick hair...it grows back within a day and is quite noticeable. Im going on a camping trip with my youth group next month...and there aren't any showers. There is only a river and we are staying in tents and bla bla bla. So how on earth am I suppose to shave? I have to shave or else I look like a hairy monster. Please help!!!