Orcas caught on camera offering humans 'gifts'
But researchers say it's a struggle to pin down one reason for the phenomenon.
Orcas
'Incredibly rare' pod of killer whales seen off Sydney beach
Witnesses described a "frenzy of activity" as the Orcas passed the boat, pursuing the Humpback whales in formation.
Grim outlook for pod of killer whales trapped by sea ice in Japan
There is no way to free the orcas, who are bobbing up and down and struggling to breathe.
Half-eaten great white likely the victim of 'picky' killer whales
A great white shark that washed up on a Victorian beach is likely the victim of a pod of killer whales.
Why killer whales won't stop ramming boats in Spain
One veteran skipper has encountered the marine mammals twice, the second time he noticed something different.
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'It would've flipped': Sailboat repeatedly rammed in 'serious' attack
When Luis first saw the unmistakable black dorsal fin cut through the water he was elated. That quickly changed.
'There's something down there': British sailor's boat attacked by apex predator
Greg Blackburn's boat was being tossed around by "heavy weather" in a notorious stretch of water, when something started slamming into the hull - repeatedly.
Rare white orca calf 'Frosty' spotted off California
It's the first time the animal has been spotted in years, and was captured from above in incredible drone footage.
Whale watchers encounter rare battle between ocean giants off WA
It was a battle of epic proportions one which saw one of the animals hurtle towards the boat at "over 30kph".
'Massive' great white spotted after surviving 'infamous' attackers
Telltale marks point towards an fierce encounter with an even more fearsome predator of the ocean.