Stunning new footage of White Island's bubbling crater lake has been captured on video by an overhead drone.

Like something out of a witch's cauldron, the video, tweeted by Geonet, shows an eagle-eye view of the slime-green crater lake bubbling aggressively.

GNS Science volcanologist Brad Scott said steam vents have been drowning in the lake over the last year, with water levels rising about 12m, causing steam-driven activity like bubbling and geysering.

He said the water in the lake is acidic and the light green colour is created from the sulphur combined with various algae and bacteria living in it.

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Scott compared the lake to the geothermal hot springs in Rotorua and Taupō, saying the same goes for those in terms of the colour they are - different bacteria, different colour.

Scientists initially noticed little pools forming in the crater in 2016, before a small lake began forming last year, he said.

When asked if there was any risk from the volcanic activity, he replied "no, not really", as the crater lake had been rising for a year now and there were no signs of increased volcano unrest.

In an article on Geonet, Scott said if the water level of the crater lake continued to rise at this rate, it would start to overflow around mid-2019. That could pose a danger to people visiting the island.

According to Geonet, scientists estimate about 75 per cent of the fluid comes from condensing steam vents under the lake. The rest comes from rainfall, which means rain has caused about 2.6m of the water level rise.