Auckland City occupies an approximately rectangular isthmus between the Waitemata Harbour and Manukau Harbour. The isthmus is only 1 km wide at its narrowest point, with a generally subdued gentle topography developed on the marine sediments of Miocene age (Waitemata Group).
   The most obvious landforms of the isthmus are the numerous, small volcanic cones (Auckland Volcanic Field) which rise abruptly above the gently rolling terrain of the urban area . The larger volcanic cones are One Tree Hill (103 m above sea level), Mt Eden (196 m), Mt Albert(134m), and Mt Wellington(135m). Several large explosion craters are prominent, and two of them have become intertidal basins: Orakei Basin and Panmure Basin.

  The Manukau and Waitemata harbours are drowned valley systems that were inundated by the post-glacial rise in sea level between c. 14 000 and 6500 years BP, and have since been largely infilled with mud, sand, and shell deposits. The shores surrounding the isthmus include many prominent coastal cliffs of East Coast Bays Formation that are up to 30 m high in places, but are interrupted by numerous small embayments. The coastal cliffs are up to 35 m high, with some sandy embayments developed from older sand spits.

In the west, the rugged, bush-clad Waitakere Ranges (up to 459 m asl), are composed mainly of volcaniclastic rocks. Waitakere City is built on the steep to rolling foothills of these ranges, and on the alluvial terraces around the harbour.

 North of the Waitakere Ranges the southern Kaipara Harbour is another downfaulted block of land, carved by erosion and later invaded by the sea.

North Shore City, also underlain by East Coast Bays Formation, includes the branched North Shore peninsula with its small scoria cones at Devonport, Lake Pupuke crater, and the hilly Birkenhead district with two tuff craters open to the harbour at Northcote.

Manukau City covers the area around the eastern margins of Manukau Harbour where extensive flat to gently undulating lowlands (up to 20 m asl) are underlain by Quaternary sediments, mainly pumiceous and organic materials. The Takanini-Ardmore lowland is the largest.
   To the east, and along Tamaki River, the lowlands merge into the dissected, rolling hill country of theWhitford-Brookby area, which rises to 100-150 m asl.

 Further south the Hunua Ranges are the highest (688 m, 2257 ft) and largest hill area in the Auckland region. They are composed mainly of the greywacke and argillite rocks that form the substratum of the region.

West of the Hunua Ranges the Franklin Volcanic Field extends from Bombay to Pukekohe and Waiuku, as well as south of the Waikato River. Like the Auckland Volcanic Field it is made of basalt, and includes small volcanoes (Red Hill), explosion craters (Pukekohe East Crater), and lava flows (the Bombay Hills).

Of all the islands within the inner Hauraki Gulf, volcanic Rangitoto is the most distinctive, with its broad, gently-sloping flanks (composed of lava flows) surrounding a central, steep-sided scoria cone (260 m asl). Browns Island (Motukorea) is also volcanic. Other islands (Motutapu, Motuihe, and Waiheke) consist of low, rolling hills of greywacke (Waipapa Group) and basal Waitemata Group sediments (Kawau Subgroup) that rise to 121 m asl and, in places, are bounded by steep coastal cliffs.