The seas around Britain are some of the most environmentally damaged in the whole world.
A study shows for the first time how years of human activities, like fishing, pollution and climate change, have affected the planet's oceans.
It shows that not one single bit of ocean has escaped some human damage and half the oceans are badly damaged.
Experts will use this information to prioritise work to protect the oceans from further harm.
One of the most damaged areas was the North Sea off the coast of Scotland, and the English Channel.
The study found the least affected areas are near the north and south poles.
Oceans cover more than 70% of the world's surface and the scientists divided the ocean into square kilometres to study it.
The map highlights 17 different causes of harm to the oceans, including fishing, climate change, pollution, oil exploration and dredging.