[1][2] It is located on the shore of a natural Harbor, Prince Rupert Bay, in Saint John Parish on the north-west coast of Dominica.

The Indian River is Portsmouth’s southern border and Cabrits National Park is located on a peninsula to the north of town.

The town’s streets were named after some notable British people of the time period: Egremont, Queensborough, Rodney and others.

[3] The Ross University School of Medicine, was located near Portsmouth, in Picard, but was relocated to Barbados, after Hurricane Maria caused extensive damages in 2017.

The area is the birthplace of Exile One's Gordon Henderson, and former Prime Minister of Dominica, Roosevelt Douglas.