In the middle of the region, there is chantaburi mountain range lying through the middle of Chonburi, Rayong, Chanthaburi. It is mostly the granite rock. A lot of gemstones are found along the range in basalt hill in Chantahburi and Trat.
Banthat Mountain range aligns along the Thai-Cambodian border in Chanthaburi and Trat. This mountain is mostly the sandstone
Alluvial plains the largest alluvial plains in the region is situated along the banks of Bang Pakong river. There are mangrove forests grown on the muddy beaches around the mouth of the river.