Rock armour (rip rap) is made up of thousands of durable rocks, such as granite, compiled together to act as a barrier between waves and the land. It is important that the rocks are large enough so that they are not moved by storm waves.
Their downward slope arrangement to the sea deflects wave energy as water can enter the gaps between the rocks.

Benefits:

Relatively cheap; rock armour is much cheaper to implement than sea walls and aims for the same effect.
The structure can be built quickly and requires little maintenance.
This method is versatile, rock armour can be placed in front of a sea wall to increase its lifespan.

Costs:

Rock armour makes access to the beach difficult, even dangerous in wet conditions or if the rocks are unstable.
Rocks are generally taken from Norway or Sweden rather than local quarries, which makes them prone to inflation and can worsen the effects of climate change.
Visually intrusive on beaches.
Can be damaged in particularly heavy storms.