Wareham is a historic market town and, under the name Wareham Town, a civil parish, in the English county of Dorset. The town is situated o…Wareham is a historic market town and, under the name Wareham Town, a civil parish, in the English county of Dorset. The town is situated on the River Frome eight miles southwest of Poole. The town is built on a strategic dry point between the River Frome and the River Piddle at the head of the Wareham Channel of Poole Harbour. The Frome Valley runs through an area of unresistant sand, clay and gravel rocks, and much of its valley has wide flood plains and marsh land. At its estuary the river has formed the wide shallow ria of Poole Harbour. Wareham is built on a low dry island between the marshy river plains.