Some shipping lanes in Canada will be changed so the rare Northern right whales will be able to swim more safely.
Hundreds of the creatures have been hit in the busy lanes and there are only about 350 left in the world.
Slow movers
They move very slowly and are the most endangered large whales on earth.
So the International Maritime Organisation has said Canada can change which shipping lanes it uses.
That means an area known as the Bay of Fundy, off the coast of Nova Scotia, will be much safer and could reduce the chances of a whale being hit by 80%.