Here's why:

* Erosion: Sea caves are formed by the erosive power of waves. The constant pounding of waves against the coastline weakens the rock, creating cracks and hollows that eventually develop into caves.

* Abrasion: The waves carry sand and pebbles that act like sandpaper, grinding away at the rock face, further deepening and widening the caves.

* Hydraulic Action: The force of the waves crashing into the cave compresses the air trapped inside, creating pressure that weakens the rock and eventually causes it to break apart.

While sea caves can be beautiful and fascinating features, their formation is ultimately a process of breaking down and wearing away the coastline, making them a destructive force.