Eastern Thailand comprises the seven provinces that lie south of Isaan and east of the Central Plains, Located between Bangkok and Cambodia.
Eastern Gulf Coast The closest beach Resorts to Bangkok, this region is an absolute tourist magnet. Its most popular destinations include Pattaya and Ko Samet, but there are also some undiscovered beaches and islands.
Inner Eastern Thailand A mountainous area on the way through to Cambodia. It can also be used as a base for Khao Yai National Park.
Trat Province The much-loved Ko Chang Archipelago, a popular island destination for beaches, palm trees and fishing villages. Some lesser known islands include Ko Mak and Ko Kut
Most visitors arrive by bus from Bangkok, but there are small airports at U-Tapao and Trat.
Information more at : http://www.tourismthailand.org