The topography of the east is characterized by three features: mountain ranges, alluvial basins, and rolling plains.
The ranges, lying lengthwise in the middle of the region, are the Chanthaburi Range and the Bantat Range.
The largest basins are the Prachin Buri-Bang Pakhong basin and the coastal plain.
There are 144 islands.
Ko Samet is a tourist attraction of Rayong Province,
Famous for its beautiful beach and coral reefs while Ko Chang and Ko Kut are in Trat Province.