I really like it when waves reach a sea wall at an angle, because the resulting criss-cross looks so cool :-)

And especially cool when you see it gradually building up, like below where the sea wall is partly protected by the gravel (or whatever you call those heaps of stones running in parallel to the sea wall?). The energy of waves hitting the sea wall at that part is dissipated, hence no reflected wave is sent off. However waves that hit the sea wall directly are reflected. Can you see how the reflections spread?

See it more easily in the movie below:

https://vimeo.com/215409582