Dee Why is a suburb

Suburb

The word suburb mostly refers to a residential area, either existing as part of a city or as a separate residential community within commuting distance of a city . Some suburbs have a degree of administrative autonomy, and most have lower population density than inner city neighborhoods...

 of northern Sydney

Sydney

Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...

, in the state of New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Dee Why is located 18 kilometres north-east of the Sydney central business district

Sydney central business district

The Sydney central business district is the main commercial centre of Sydney, New South Wales, Australia. It extends southwards for about 3 kilometres from Sydney Cove, the point of first European settlement. Its north–south axis runs from Circular Quay in the north to Central railway station in...

 and is the administrative centre of the local government area of Warringah Council

Warringah Council

Warringah is a local council area in the Northern Beaches region of Sydney, Australia. Warringah Council overlaps with a number of suburbs from the Manly Council area to the south and the Pittwater Council area to the north...

, and along with Brookvale

Brookvale, New South Wales

Brookvale is a suburb of northern Sydney, in the state of New South Wales, Australia. Brookvale is located 16 kilometres north-east of the Sydney central business district, in the local government area of Warringah Council and is part of the Northern Beaches region.-History:The first development in...

 is considered to be the main centre of the Northern Beaches region.
The origin of the name of neighbouring Long Reef is obvious, but the reasons for Dee Why's name remain unclear.