This phenomenon is really unique and it happens only in the city of Skagen in Denmark. In a sea beach called Grener two seas are meeting, the North Sea and the Baltic Sea, creating a visible sea line. The Baltic Sea is cold, whilst the North Sea is warm. So when you stand at the meeting point, you feel one side is cold while the other side is warm. The two opposing tides in this place can not merge because they have different densities.