Mangroves are adapted to live in salt-water-saturated sand at the shore's edge. They send roots up to absorb oxygen (and even nitrogen) directly from the air. Ecologically, mangroves are one of the most important type of tree in existence. They filter the water and are able to remove or lock up many pollutants. It's my understanding that prior to human habitation, most Pacific islands were ringed by large mangrove forests. Today only small remnants of these forests remain. Many Pacific islands have totally lost all mangrove trees. We are lucky here on Saipan to have a small but apparently healthy mangrove stand along the lagoon near Outer Cove.