Experts say there is significant concern that White Island's volcano could erupt with little or no warning.
GNS has evidence that hydrothermal activity in the hot lake has increased.
White Island is 48km from the Bay of Plenty coastline, so while it wouldn't be a threat to people on the mainland, it could be to tourists who frequently fly overhead.
GNS says large amounts of sediment are coming to the lake surface, often with white steam and gas flashing from around the lake's base.
The state of unrest at White Island is increasing, and eruptions are possible with little or no warning.
Reporter: Mihingarangi Forbes