My next memory involves being at the bottom of a Costa Rican river wondering which direction was up and holding my breath while I waited for my life-preserver to sort things out which it did.

WSJ: Dilbert Creator Scott Adams's Year Without Fear

The memory helps the fish find its way back to the mouth of its home river, and from there it uses chemical cues to locate its birth stream.

BBC: Sockeye salmon 'sense magnetic field of home'