How do killer whales move?

Answer 1

Killer Whales (Orcas) propel themselves with their tail which have to very large horizontal flukes on them. The motion they employ to accomplish this is a vertical up and down motion similar to what humans do when doing sit-ups.
An orca moves in the same way a dolphin does. They move their flukes up and down. The flukes are the flat part on its tail. As it moves its tail up, its muscles tighten. As it moves down, they relax.
The Orca has large flukes (its tail) that move up and down to generate thrust and motion through the water. It is has a top speed of over 30 knots, and can, with a bit of a run, launch its multi-ton body completely clear of the water in a maneuver called breaching. A link is provided.
Orcas move by lifting and dropping their tail. They also have a dorsal fin on their back is so they do not roll in the water when swimming, and the flippers are used for turning.