Onepoto is the name of a volcanic explosion crater (or maar) in North Shore City, New Zealand. It is a part of the Auckland volcanic field.
Located near the approaches to the Auckland Harbour Bridge, it was created by a series of eruptions approximately 250,000 years ago. The crater first became a freshwater lake, and later became a tidal lagoon when sea level rose to the present level 7000 yrs ago after the last ice age. The crater's floor has been reclaimed, with recreational sports fields and a pond, and some parts of the tuff ring were quarried away in the 1950s to provide fill for the Northern Motorway.[1]