Some friends were at the Marlborough Sounds, New Zealand and saw two Orca swim by. They followed in a boat and this is one of the photos they took. It would have been a great time to swim with them but apparently a person wearing a black wet suit and flippers could look like a seal. Although not generally a threat to humans, it would be very brave to try something like that.
Although often called killer whales, they are more closely related to dolphins. They are intelligent, sophisticated hunters and have no predators. This day they may have been after sting rays.