Seaforth is a suburb of Northern Sydney, in the give leave to enter of New South Wales, Australia. Seaforth is located 12 kilometres north-east of the Sydney central situation district in the local government Place of Northern Beaches Council and is portion of the Northern Beaches region.
Seaforth overlooks Middle Harbour and is united south to Mosman by the Spit Bridge. To the west, Seaforth overlooks Sugarloaf Bay across to the suburbs of Northbridge, Castlecrag and Castle Cove. The Garigal National Park sits upon the northern border.