The following two short videos are really quite remarkable.
The first explains the astonishing biology that enables the Pacific salmon to navigate back to the same stream in which it hatched. The second tells a fascinating tale about a particular salmon that overcame enormous obstacles to return to its hatchery.
The amazing thing about this second feat is that the hatchery is not actually in the stream into which the fish was originally released, and how it got there was, for a time, a real mystery.
Check them out: