If you don't want to lose something when canoeing, make sure it is tied down during your canoeing trip. If canoes capsize, everything that isn't tied down goes into the water and will be difficult or impossible to recover.
Carry cameras, binoculars, valuables, snacks or lunches in a watertight container, preferable one that floats (just in case). Avoid using glass containers. And always, always wear a personal floatation device. Canoeing is a great way to enjoy wildlife and adventure travel, but you should always plan ahead.