This video says about itself:
13 January 2015
An underwater volcano off Tonga was spewing ash high into the air on Tuesday, causing several carriers to suspend air travel to the South Pacific island nation and turning the surrounding ocean blood red, residents and officials said.
The Hunga Tonga-Hunga Ha’apai underwater volcano, located about 65 km (40 miles) north of the capital Nuku‛alofa, was sending volcanic ash up to 4,500 meters (14,765 feet) into the air, the Wellington Volcanic Ash Advisory Centre (VAAC) said.
The volcano, which first erupted in 2009, had been rumbling in recent weeks before exploding violently in the past few days, The New Zealand Herald newspaper reported.
Tonga’s Hunga Ha’apai eruption forming new island
Updated at 12:50 pm on 16 January 2015
The new island is more than 1 kilometre wide, 2 kilometres long and about 100 metres high, and is now joined to Hunga Ha’apai.
Tongan government officials say the volcano is erupting about every five minutes, spurting dense ash and rocks about 400 metres into the sky and a steam plume to about 1000 metres.
The ash is very wet and being deposited close to the vent, building up the new island.
Scientists and Tongan authorities plan to travel to the island by boat today.
“If there’s no danger during our assessment and we think we can land, we might land to sample some rocks,” said Taniela Kula, deputy secretary of the Ministry for Natural Resources.
“Also, we’re doing testing of the water, acidity of the water and also pH round the area, just to see the effects of the activity.”
He said ash fall and acidic rain has been observed within 10 kilometres of the eruption and leaves on trees in the area are dying.
Two New Zealand GNS scientists in Tonga have been reviewing images and videos and hope to get close to the new island.
Hundreds of travellers were delayed by flight cancellations due to the volcano this week as flights from New Zealand and domestic services were disrupted.