Motukorea or Browns Island is a small New Zealand island, in the Hauraki Gulf north of Musick Point, one of the best preserved volcanoes in the Auckland volcanic field. The age of eruption is about 25,000 years ago, when the Tamaki Estuary and the Waitemata Harbour were forested river valleys. Due to centuries of cultivation, little native bush remains except on the north-eastern cliffs, leaving the volcanic landforms easily visible. It exhibits the landforms from three styles of eruption. The island consists of one main scoria cone with a deep crater, a small remnant arc of the tuff ring forming the cliffs in the northeast, and the upper portions of lava flows. The area was dry land when the eruptions occurred, but much of the lava is now submerged beneath the sea.