When summer comes, people like to go to the beach and play in the seawater. It is such a good way to drive away the hotness. But it has been reported that many people drawn while they were swimming on the beach. The people who died were good at swimming, the reason they got killed was the invisible demon under the seawater. In the afternoon, there are some vortexes under the seawater, which people can’t see. When people go swimming, they will be absorbed by the vortexes, even though they are good at swimming, they can’t resist the strong power. So when we go to play in the beach, we must take care.