From their website:
A diorama base to enable you to create a realistic assault by sea. The Diorama has a well detailed sea, with beach, and a raised platform area bordered by rock and sloping ground. The platform area has been left un-detailed to allow the modeler the scope to create defensive positions.
The sea can be extended with S227 sea section.
Dimensions: 60cm L x 33cm W x 3cm H