A large eruption occurred at 14:11 on 9 December 2019, which resulted in 22 fatalities, including two people who were missing and ruled to be dead by a coroner.

In addition, four sea stacks collectively known as Te Paepae o Aotea or Volkner Rocks lie 5 kilometres (3.1 mi) northwest of Whakaari / White Island.

[9][13][10] The modern crater floor of Whakaari / White Island lies less than 30-metre (98 ft) above sea level and is largely covered by material from the 1914 debris avalanche.

The bathymetry surrounding the emergent summit of Whakaari / White Island consists of a broad, sloping shelf extending from sea level to approximately 80-metre (260 ft) depth.

Based on extrapolating 20 m GIS contour data to enclose the present crater and upwards with a maximum slope angle of 30°, the former pre-collapse summit was inferred to have been 500–600-metre (1,600–2,000 ft) high.

Side-scan and bathymetric data indicate possible debris flows associated with its collapse that can be traced back to the current crater on White Island.

Another debris flow exited the modern crater on the northern side of Troup Head and through several submarine valleys towards the east into deep water.

As a result of the collapse of the former cone of the White Island Volcano, it is suspected to have generated a 7-metre (23 ft) high tsunami that flooded the coast of Bay of Plenty as much as 7 kilometres (4.3 mi) inland between 3,000 and 2,200 B.P.

[10] For the past few thousand years, Whakaari / White Island has been the location for an open, highly reactive hydrothermal system.

This hydrothermal system expresses itself as hot springs and mud pools, fumaroles, and acid streams and lakes.

The present centre for volcanic activity and outgassing is a large crater lake of boiling acidic waters located in the western subcrater.

The intermixing mélange of marine waters, meteoric waters, and hot magmatic fluids generate acid brines, with pH as low as 2, that outgas and form numerous and often transitory hot springs and mud pools, fumaroles, and acid streams and lakes.

The crater lake of boiling acidic water, which occupies the western subcrater, appears to vary in volume due to changing meteorological conditions and fluctuating levels of hydrothermal activity.

[16][17][18] Although Strombolian activity occurred from the late seventies to the mid-eighties, explosive eruptions at Whakaari / White Island are typically phreatic or phreatomagmatic in style.

[17][18] Whakaari / White Island's frequent activity and easy access attract scientists and volcanologists as well as many tourists.

[10][20] For example, this volcano provides a readily studied example of the type of volcanic magmatic–hydrothermal system involved in the generation of porphyry copper deposits.

Survey pegs, magnetometers and seismography equipment for early earthquake warnings via radio were installed on the crater walls in 1976.

In March 2000, three small vents appeared in the main crater and began belching ash which covered the island in fine grey powder.

Between July and August 2012 the island showed signs of increased activity with lake and gas levels rising from inside the crater.

[37] The ongoing seismic and volcanic activity in the area and subsequently heavy rainfall as well as low visibility and toxic gases all hampered recovery efforts.

[38][39] Experts identified the event as a phreatic eruption: a release of steam and volcanic gases which caused an explosion, launching rock and ash into the air.

Visual observations conducted in January showed that lava had been extruded into the vents created by the eruption on 9 December.

[41] The Māori name Whakaari is recorded in multiple 19th century texts by Europeans, with one mention dating back to 1849, though spelling varied including Wakaari, Whakari, and Whaka ari.

[46] Mining came to a halt in September 1914, when part of the western crater rim collapsed, creating a lahar that killed all 10 workers, who disappeared without a trace.

[49][50] In 1923, mining was again attempted but, learning from the 1914 disaster, the miners built their huts on a flat part of the island near a gannet colony.

Each day they would lower their boat into the sea from a gantry, and row around to the mining factory wharf in Crater Bay.

[citation needed] Before the days of antibiotics, sulphur was used as an antibacterial agent in medicines, in the making of match-heads, and for sterilising wine corks.

[42] In 1874, the island was sold to the partnership John Wilson and William Kelly by the estate of Retireti Tapihana (Tapsell).

Yellowtail kingfish abound all year, while there is deep-water fishing for hapuka and bluenose (a type of warehou) in the winter.