History of a tide...

Beginning. The ocean is flat, no movement, no perturbation, a mirror surface. We are in the middle of the ocean, at some point in the South Pacific. And here comes a depression, a hole in the atmosphere density. But nature doesn't like the holes and thus wants to fill it. In another place, there is a high density point, thus the particle start to move to equilibrate the density. As the air travels , a wind appears and creates ripples on the surface of the ocean.

It all starts chaotically, but as the wind goes on, the peaks and the troughs gain order and start their long travel through the seas. Actually, only the energy of this wave will really travel, the way the particles are only describing a vertical circle in the sea.   The characteristics of the swell are determined by the force and the stability of the wind. A long and powerful wind will create a big and steady swell. During its travel, winds, currents and reefs continue to shape this wave. At this point, it is important to notice that the wave is often spread over hundred of meters and doesn't measure more than a few centimeters in height. It's speed is huge at this point as the water is very deep.

While approaching the coast, as the water height gets lower , the wave start to slow down. And as it slows down, the wave regroups and become tighter and thus higher. Then, the wave takes it final shape, depending on the bathymetry of the ocean floor, aka the structure of the ground. As the wave gets to the coast, the water gets so low that the wave reaches a breaking point and gives birth to a tide and dies on the beach. The break point of the wave can be the same on all its length or can be gradual, from one side to the other. The configuration of the ground plays a large role in this aspect.

The gradual breaking point is a key point for surfers to get a nice run as they surf  almost exclusively at this point. Thus a long break is better as the run is longer. The implication of the ground floor on the breaking point of the waves explains a little why some places are called surf spot. Indeed, a nice beach with a rocky ground can have a more consistent breaking point for waves than a beach with an always changing sand floor.