Communication to the remote Pacific nation remains limited following Saturday night's eruption of the Hunga Tonga-Hunga Ha'apai volcano, though power is being restored.
In the absence of confirmed reports of death or harm, New Zealand officials report coastal damage from storm surges in the wake of the blast.
Prime Minister Jacinda Ardern said boulders and boats had been washed ashore on Tongatapu, the largest island and home to the capital, Nuku'alofa, around 65 kilometres south of the volcano.
"Seeing some of those waves come in and peeling back fencelines and structures, you can see the force of those surges," Prime Minister Jacinda Ardern said
"Everyone just wants to establish how wide scale that impact has been."
The blast also caused a tsunami across the Pacific Ocean, sending large waves to Japan, the US and Peru, while a sonic boom could be heard in nearby Pacific nations.
Tonga, with a population of 105,000, is comprised of 169 islands, a few dozen of which are inhabited, and Ms Ardern said communication links were yet to be established across the archipelago.
Pacific Peoples Minister Aupito William Sio said key members of Tonga's royal family were safe and well.
"We want to be in Tonga and on the ground as soon as we are possible able to be," Ms Ardern said.
Volcanic ash in the air and on the runway in Tonga prevented an aerial mission in the immediate aftermath of the blast.
Just prior to 9am NZDT on Monday morning, a Defence Force Orion aircraft took off from Auckland's Whenuapai base on a mission to investigate further.
Foreign Minister Nanaia Mahuta said the restoration of communication links with New Zealand's High Commission allowed confirmation the flight would be safe to depart and land.
"Things are calm (but) there is significant ash fall," she told Radio NZ.
"80 per cent of power has been restored however internet connection and communications remain an issue."
The aircraft will also carry water, food and medical supplies.
University of Auckland volcanologist Shane Cronin said the eruption was likely to be the world's biggest for three decades.
"Our research into these earlier eruptions suggests this is one of the massive explosions the volcano is capable of producing roughly every thousand years," he wrote in The Conversation.
"We found evidence of two huge past eruptions ... and then used radiocarbon dates to show that big caldera eruptions occur about ever 1000 years, with the last one at AD1100."
Aid agencies including Save the Children and Oxfam say they are ready to offer support.
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