Cape Northumberland is a headland in the southeast of the Australian state of South Australia.

[1][3][4] Cape Northumberland was named after Hugh Percy, Duke of Northumberland, by the Royal Navy officer, James Grant, on 3 December 1800, when he was mapping the southern coast of Australia aboard HMS Lady Nelson.

Because it was being undermined by the sea, a new lighthouse was constructed in 1882, about 700 metres (2,300 ft) further inland.

[5][1][3] The cape is located on the southeast coast of South Australia.

[1][2]: 4  The cape was described in 2017 in an American source as being "about 30 metres (98 ft) high, is rugged and cliffy, with a hill rising to an elevation of 41 metres (135 ft) behind it.