Water, water everywhere and not a drop to drink! This line from The Rime of the Ancient Mariner by Samuel Taylor Coleridge illustrates the dilemma faced by plants living on our sea shores.  Although there is plentiful water, the high salt concentration means that very little of it is readily available to plants. Many species have adapted their leaves to store water, so have a succulent appearance.

Fleshy leaves of Cakile maritima