 The Bedrock Plain has rolling hills with low relief and several large rivers.The Coastal Sands are dunes at the ocean's edge cut with meandering rivers, ribbon lakes, and a series of lagoons and bays which vary in size from a few to two dozen square kilometres.The Coastal Sands can be further subdivided into the Andriambe, Ebakika, Efaho, Fanjahira, Lakandava, Lanirano, Manampanihy, Mandromodromotra, Vatomena, Vatomirindry and Vatorendrika basins.