Mother nature has yet another naturally occurring gem of beauty to add to her long list of incredible sights in this world. Just when we humans think we own this planet, nature boldly reminds us that we share it with other forces.
Off the west coast of France, the tourist destination Ile de Ré is a 30 km long, 5 km wide island that experiences a strange and eye-catching occurrence.
Already a popular spot for Parisians to spend their summer, this little Atlantic-coast island is a tranquil, low-key but uber-chic alternative to city life. With long beaches, cycle paths and lots of towns and villages, it’s packed with visitors from the start to the end of the season.
Right off the shore, it also happens to be where a “cross sea” forms. According to surface navigation, the cross sea phenomenon occurs when two traveling wave systems, coming from different directions, meet at oblique angles. This convergence forms square-looking shapes in the water. The waves created by the new wind form and move at an angle that crosses the first set of waves to create a shift, resulting in repetitive geometric patterns, similar to that of a chessboard.
Because both sets of waves can match in strength, the combined force is exponentially more treacherous for anyone caught in its path. In an emergency situation, lone swimmers are told to swim parallel to the current to escape it, but with the currents running perpendicular to each other, you have to fight it, which can be near impossible. Only when one set of waves tires out – it’s usually the first set that tends to dissipate – the cross sea becomes less dangerous.
However, it does make for some excellent sightseeing. Another place of interest where this phenomenon exists is at the northernmost tip of Denmark, Skagen, where the North Sea and the Baltic Sea meet, creating a similar effect.