Narwhal are relatively small whales (16~18ft or so) that live entirely way up in the Artic.
The males grow a large tusk that can be feet long! Thus they are known as the unicorns of the ocean.
It's actually pretty tough to get a picture of them with that tusk sticking up. They normally
don't stick it out of water as they swim. They are still heavily hunted today, unfortunately.

Just outside Baffin Bay near Pond Inlet, Canada
June 2018