A species of whale which was thought to be going extinct is making a comeback, according to an environmental expert.
The grey whale is still endangered but their numbers are increasing, and there are now thought to be around 20,000 in the world.
One of the big dangers for the whales is climate change, because rising sea temperatures affects where they can find food.
Grey whales grow to around 13.5 metres long and can live to 40 years.
The study of whale numbers was made by an environmental protection officer from Mexico.