Mr Sye, who had been to the area last week with another group of pupils, was in Wellington yesterday but was able to broadcast the good news to worried families who had begun flooding school telephones with calls.
But what had been a moment of fear back home was being taken in stride by the children, as they got "fantastic photos and fantastic footage", Mr Lowes said.
"The ash cloud rose and rose," before the wind began to disperse it away from the group, which had arrived in the area aboard two Nimons buses on Monday and is due back at the school tomorrow afternoon.
After the mountain silently blasted ash and gas two kilometres into the sky on the western side of the mountain, police and Department of Conservation (DoC) staff closed the Tongariro Alpine Crossing at Ketetahi and Mangatepopo roads..
DoC community relations manager Kim Alexander-Turia said about 50 people were thought to be on the crossing at the time of the eruption. All were thought to be safe.
GNS Science duty volcanologist Nico Fournier said there was "essentially one explosion, and it was not sustained".
Little effect was being seen in Hawke's Bay last night, although there was some disruption of flights between Napier and Auckland.
One early evening arrival was 50 minutes late, and passengers on the back flight to Auckland were told it was being rerouted to avoid any possible ash cloud and would take about one hour, 45 minutes, rather than the usual hour, and one flight in each direction was cancelled.
Hawke's Bay Civil Defence emergency management controller Ian Macdonald said late in the afternoon ash was falling northeast of the mountain and was not expected to affect the Bay.