They are adapted to life in a saline medium. Osmoregulation is achieved by specialized epidermal cells and the leaves have no need for stomates, as opposed to terrestrial plants, because all of the gas-exchange is accomplished through the epidermis.
Sea grasses have the ability to grow when completely submerged.
Surf grass have a successful anchoring system to withstand tidal currents and moderate wave action.
Sea grasses are able to reproduce in an aquatic medium. This adaptation called hydrophilly, which is unique to aquatic plants, allows the surf grass to perform both surface and completely submerged pollination.