What are the undercurrents of seawater?

The so-called seawater undercurrent refers to the changes of seabed topography, such as the appearance of sand dunes and some abnormal flows of seawater, which will pose a great threat to people who are swimming.

In the undercurrent of seawater, the most dangerous thing is the "rip current". The reason for this seawater flow phenomenon is shown in the animation below. Because there will be some small sand dunes on the seabed, when the sea water flows to the coast, it will gather at the seaside, and then it will find the gap between the sand dunes to flow out, because this position has the largest gap.

This tearing current is far away from the coast, and the current is very fast, which makes people too late to react. When people react, they may have been rushed out far away.

After being washed away by rip, some people will swim to the shore when they are nervous, but this rip flow is persistent, so they will soon be exhausted and finally washed away.

According to statistics from the United States, more than 150 people died in rip current in the United States alone, accounting for more than 90% of drowning accidents at the seaside. It can be said that it is a veritable "first killer".

According to the course of Marine Disaster Reduction Center of China Ministry of Natural Resources, once you are involved in rip flow, don't be nervous, don't swim hard in the water, which will consume your physical strength, especially don't swim against rip flow to the shore, which will only be futile and waste your physical strength.

Instead, you should drift along the rip current, swim parallel to the coast after you feel that the rip current has slowed down, walk out of the affected area of the rip current, and then slowly approach the shore. If you have the chance, you should ask others for help at the seaside.