Barriers and Breakthroughs
There are many different kinds of barriers which can have either a positive or negative effect. These old groynes were intended to stop coastline erosion and protect beach habitat.
As you see, they are now broken down in many places and no longer really functional. The word groyne (groin in the USA) comes from the Old French groign and Late Latin grunium meaning ‘snout’ which is appropriate as it sticks out from the shore into a body of water!