Parts of New Zealand are under tsunami advisory after a violent eruption of the Hunga-Tonga-Hunga-Ha'apai underwater volcano in Tonga this afternoon.
There advisory is in place for the north and east coast of the North Island and the Chatham Islands.
National Emergency Management Agency said people in those areas might experience strong and unusual currents and unpredictable surges at the shore.
People are being urged to stay away from beaches and shore areas until 4am Sunday.
There is no need to evacuate other areas unless directly advised by local civil defence authorities.
A tsunami warning for all of Tonga was issued just after 5.30pm by the Tonga Meteorological Services.
There is also a tsunami advisory in place for Samoa, Fiji, Vanuatu and a marine warning for parts of Australia.
Tonga's King Tupou VI has been evacuated from the Royal Palace after a tsunami flooded the capital Nuku'alofa, following another volcanic eruption.
Local media report a convoy of police and troops rushed the King to a villa at Mata Ki Eua as residents headed for higher ground.
As well as the palace grounds, the waterfront and main street were flooded in Nuku'alofa.
There are concerns about some of the other islands, especially the Ha'apai group which is very low lying.
Earlier, explosions were heard as the volcano Hunga-Tonga-Hunga-Ha'apai erupted for eight minutes, throwing clouds of ash into the sky.
US Stormwatch has tweeted the eight-minute eruption is one of the most violent ever captured on satellite.
Tonga Geological Services says the plumes of gas, smoke and ash reached 20 kilometres into the sky.
It is the latest in a series of eruptions of the Hunga Tonga-Hunga Haʻapai volcano, which is 65 kilometres north of the capital..
The latest explosions were heard even in New New Zealand, more than 2300 kilometres away, and as "loud thunder sounds" in Fiji, 500 kilometres away.
New Zealand forecaster Weather Watch tweeted: the energy release was simply astonishing, with reports of people hearing the sonic booms throughout New Zealand.
Here's how things unfolded: