By Roland Pease
BBC science correspondent
A great white shark crossed the Indian Ocean from South Africa to Australia and back again within just nine months.
The shark may have made the journey to find a mate
It was one of several great whites tagged by researchers in an attempt to improve conservation strategies.
Writing in the journal Science, they say the journey is unparalleled among fish - only tuna come close.
The mere act of tagging a great white is something of a feat; several people need to hold the creature still while the satellite tracker is attached.
This device was fixed to the female shark's trademark dorsal fin. Thankfully no scientists - and no sharks - suffered during the tagging.
EPIC OCEAN JOURNEY
The project will inform future conservation strategies
The conservationists were investigating how far great whites wander, to see what protection measures might be needed to save them from extinction.
Several of the sharks migrated from South African to Mozambiquan territorial waters - where they are not protected.
But Ramon Bonfil of the Wildlife Conservation Society in New York, US, and colleagues were stunned by the epic journey of the shark they called Nicole - after the shark-loving Australian actress Nicole Kidman.
"We suspect that she went for reproductive reasons," Dr Bonfil said.
"There's plenty of food around South Africa and she would be using too much energy to just go to Australia to feed. Of course we can't prove this at this stage, it is just a hunch."
Great whites were once thought to keep to coastal regions, but this was a trek across a vast expanse of open ocean.
The journey was very direct, not some aimless wandering. And the stay near Australia was only brief.
The researchers say the fact that they saw a shark make the journey at all - after observing only about 20 animals - suggests it is common behaviour.
Their concern is that such migrations make the great whites vulnerable to long-line fishing.
It is already known that lesser sharks do get captured and killed this way.
Given that the great white's population is small anyway, the species can ill afford to lose numbers in this way.