Oil at sea can be a problem. In 2010, BP’s Deepwater Horizon spill discharged 4 million barrels of oil into the Gulf of Mexico, of which only 810,000 barrels of oil were collected. It was the largest marine oil spill in history. As a result, much of the oil was washed ashore by the tide making the beach dirty and causing massive problems for wildlife. But how do we explain a disaster of that scale to children and what is the science behind it?