Underhill is the name given to the area of very steep land, at the northern end of the Isle of Portland in Dorset, England, which contains the villages of Chiswell, Castletown and Fortuneswell. The remaining part of the island is known as Tophill.
Underhill is the term used to describe the area of extremely sloping land, located at the northern tip of the Isle of Portland in Dorset, England, which comprises the villages of Chiswell, Castletown, and Fortuneswell. The rest of the island is referred to as Tophill.