Geysers twice the height of an adult giraffe are exploding from the crater lake at Whakaari/White Island.
But volcanologists say there's nothing to worry about at this stage, and on a scale of zero to five, the volcanic alert level remains at one.
"The rising lake level has impacted the surface activity around the active vents on the west side of the crater floor," GNS Science volcanologist said on Thursday morning.
"Geysering-type activity has become established in the main active vent due to hot steam and gas passing through the now drowned active vent area... Normally the gas and steam would vent directly to the atmosphere, now it's through the water in the vents and is visible as the geyser-like activity."
Volcanologist Brad Scott told Newshub there are two reasons why the crater lake would rise.
"One is climate and rainfall, and we've had a lot of rainfall lately. The second is volcanic gas and steam coming into the volcano and being condensed and turned back from the vapour phase into water. It's a combination of those two."
At 10m high, the "muddy, geyser-like explosions" are no threat to visitors.
"When the public is up by the active crater and looking down into it, they'd be in the order of 250m, 280m away," said Scott.
GNS Science is continuing to monitor the island, which is New Zealand's most active volcanic cone. Its last proper eruption was in April 2016, and a few months later in September ash was "passively emitted" from a vent formed during 2012's eruption.
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Because the current geysers are only happening because the water level is so high, there are no plans to change the volcanic alert level or aviation colour code yet.
"We'd have to see monitored parameters indicative of change and unrest - that may be a change in the amount of gas coming out, the type of gas coming out, a change in the seismic activity, a change in the temperature of the lake," said Scott.
"There's a whole pile of different parameters that we monitor, and we'd have to see two or three of those parameters changing and indicating an increase in volcanic unrest - and we're not seeing that at the moment."
The alert was briefly raised to two in June after recording increased levels of gas and earthquake swarms. It was lowered back to one after testing showed the quakes were tectonic, not volcanic.
More than 10,000 people visit White Island every year.