...typing for peace, democracy, and the glory of the Typosphere
A secondhand Canon waterproof D10 or D20 loaded with CHDK and mounted on an expendable tripod that you could stick into the muck of the riverbed would do it. Only problem would be either having to camp next to it or risk someone walking off with it during the day's shoot.http://chdk.wikia.com/wiki/D10
Neat looking shell. Time lapse would be neat if you could find a place and a camera.