[4] A feature of the field is that it was always underwater, but some of the cones formed islands in the historic sea and then have been eroded with characteristic flattened tops.

[1] The resulting seamounts were finally all buried about the time that Banks Peninsula was formed in the late Miocene.

The area of the field is about 1,520 km2 (590 sq mi) and the presence of the volcanoes is relevant to mineral and other potential exploitation of the Canterbury submarine basin.

[2] The detailed understanding of the field results from bore hole and seismic data accumulated over many years of geological mapping.

The name Maahunui relates to the canoe of Maui which (according to Māori legend) became the South Island of New Zealand.