Sumoto is a city located on Awaji Island, Hyōgo Prefecture, Japan. As of 1 June 2022, the city had an estimated population of 42,094 and a population density of 230 persons per km². The total area of the city is 182.38 square kilometres (70.42 sq mi).

Awaji Island is an island in Hyōgo Prefecture, Japan, in the eastern part of the Seto Inland Sea between the islands of Honshū and Shikoku. The island has an area of 592.17 square kilometres. It is the largest island of the Seto Inland Sea.