Gray whales, Escrichtius robustus, are commonly seen off the coast of California as they typically migrate from Baja, their winter mating and birthing grounds, to Alaska, their summer feeding grounds where they gorge themselves before they head back south. This annual round trip migration makes them one of the longest migratory mammals traveling 10,000 to 12,000 miles every year, but one individual male broke the all time long distance record when he was reported off the coast of Namibia at least 13,000 miles away!  What is a gray whale doing that far from home? Although this journey occurred in 2013 it was recently confirmed using genetic testing which found he was a 40 year old male that belonged to the western North Pacific gray whale group and began his journey in Prince William Sound confirming a new world record - 16,700 miles. This sighting also marks the first time a gray whale has been spotted in the southern hemisphere. There is much we do not understand about why whales sometimes journey far from their normal range and this time scientists speculate it could be contributed to a lack of food or the fact that melting ice in the Arctic gives them greater opportunities to explore.

Sources:

www.nationalgeographic.com/animals/article/gray-whale-swam-halfway-across-the-world-setting-a-new-record?

General information about gray whales: