The female whale's incredible journey began off the coast of Brazil and ended at Madagascar, almost 10,000 kilometres (6,200 miles) away.
It was photographed there two years after first being identified by researchers on Abrolhos Bank, Brazil, in August 1999.
Scientists do not know whether the whale's epic trip was deliberate or the result of a navigational accident.
Such a long trip is unexpected in a female, because it is more normal for male mammals to wander in search of mates. The whale, known as Antarctic Humpback Whale Catalogue (AHWC) no 1363, was recognised by its distinctive markings.
Researchers led by Dr Peter Stevick from the College of the Atlantic, in Maine, US, wrote in the Royal Society journal Biology Letters the distance travelled was the "longest documented movement by a mammal".