A gray whale has made its first ever appearance in the Southern Hemisphere, as one was spotted off the coast of Namibia.
It is also unique because it is the second-known gray whale to have been documented swimming through the Atlantic Ocean in modern times. Another one was spotted in 2010.
Scientists are describing the sight as "the most amazing sighting in the history of whales."
The Southern Hemisphere has no history or fossils indicating gray whales ever existed there.
It might have arrived in the odd area by traveling through the Northwest Passage, which has been free of ice for four years straight due to climate change.
"It is tantalizing because it's a mystery," Alisa Schulman-Jangier, a researcher with the American Cetacean Society, said. "We don't know how this whale got so far from where gray whales are supposed to be."
A gray whale sighting is rare as there are only two existing populations. One is a recovered population of 22,000 in the eastern Pacific. Another is an endangered population of 130 animals in the western Pacific.
"The question now is, 'what is the origin of this whale?'" John Paterson asked on his website. "Is it another individual that has traversed the Northwest Passage or perhaps traveled around the southern tip of South America and across the Atlantic?"
Schulman-Jangier believes it is unlikely that the whale traveled around the southern tip.
She believes the whale took the Northwest Passage.
"It just makes more sense because there are so many gray whales up in that area during the summer," she said. "It makes less sense that a whale that's supposed to travel only as far as Baja would keep going and swim all the way down to the tip of South America, near the Antarctic, and enter the Atlantic that way."