It’s one thing to know that waves build up as they run from the open ocean over the shelf onto a beach, and that they build up as the water gets shallower and shallower. But we are so used to seeing exactly that (because that’s what the sea is supposed to look like!) that we don’t really notice it any more, at least most of the time. But below is an interesting case: Waves are running onto the beach, but there is also a headland going out into the sea. So in addition to running onto a beach, there is also a depth gradient along each wave crest (do you know what I mean?).

Watch the movie below to see that there are hardly any waves visible when you look at the open water on the left, but that the crests and troughs become clearly visible as soon as you are close enough to the headland where the water is shallow enough: One and the same wave crest builds up a lot more the closer you look to the headland than it does in open water.