White Island's highly-toxic crater lake has been captured bubbling away in a spectacular new video.
The large lake is full of liquid "more acidic than battery acid", creating a stunning - but deadly - sight.
Scientists first noticed collections of little pools forming in 2016, before the lake started merging together in 2017.
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"In the past few weeks, water has ponded on the floor of the active crater and started to reform a permanent lake," GNS Science said at the time.
"Volcanic activity is confined to the gas-rich vents on the western side of the active crater."
Since then, water levels have risen about 12-metres, drowning several fumarole vents and emitting clouds of steam.
In 2018, "loud sounds" were heard coming from vents in the main crater of the volcano, and GNS Science said they would keep an eye on the volcano in case it becomes more active.
Now drone monitoring has resulted in an "amazing" video showing the green lake seething away like an angry cauldron.
The green colour is caused by "lots of sulphur" heated to around 120degC or more. Volcanology scientist Dr Geoff Kilgour says the lake is more acidic than battery acid, with a pH of zero.
"It's nasty stuff - not something you'd want to swim in," he told Newshub.
In 2018, GNS warned the overflow of the lake could pose a danger to people visiting the island.
"This danger relates to a large stream flowing across the main crater floor," scientists warned.
"The danger is mitigated, however, by the low probability of the lake outlet failing and a flood occurring."
The lake is currently 11-metres from the overflow level, although recently decreasing, and volcanologists are on site testing for changes.