Chiswell, sometimes, is a small village at the southern end of Chesil Beach, in Underhill, on the Isle of Portland in Dorset. It is the oldest settlement on the island, having formerly been known as Chesilton. The small bay at Chiswell is called Chesil Cove, and the beach promenade and sea wall which form Chiswell's coastal defences are a prominent feat…Chiswell, sometimes, is a small village at the southern end of Chesil Beach, in Underhill, on the Isle of Portland in Dorset. It is the oldest settlement on the island, having formerly been known as Chesilton. The small bay at Chiswell is called Chesil Cove, and the beach promenade and sea wall which form Chiswell's coastal defences are a prominent feature.