In 2010 I made a visa-run to Cambodia and visited the coastline of Chanthaburi with many hidden beauties. The city itself is a mix of a modern provincial town and an old merchandise town from the old days of the gem trade. The seaside behind Chantaburi town is a beautiful area of rivers, mangroves and beaches, with many small fishing villages. A area highly recommended to go, but you will need your own transport.