TERRIFYING footage shows the moment a lava bomb crashed through a tourist boat and injured 23 holidaymakers off Hawaii's Big Island yesterday.
One woman on the Lava Ocean Tours vessel was rushed to hospital in a serious condition while 22 others suffered brunes and scrapes, officials confirmed.
The tourists had paid to get a closer look at the lava plunging into the ocean from the Kilauea volcano which has been erupting since May.
They were still on the water when a "basketball sized" lava bomb punctured a gaping hole in the boat's roof, the Hawaii County Fire Department said.
One woman, in her 20s, suffered a broken thigh bone and had to be taken to the Hilo Medical Center, in Honolulu, for further treatment.
A passenger on board the boat told local news station KHON2 that she and her boyfriend watched in horror as fiery rocks flew toward them.
She said: "It was just surreal. I didn't even believe that this was coming towards us. We've been watching it.
"It was so beautiful. Then it's like, oh my God. I need to get away from this. There's nowhere to go."
The US Geological Survey says explosions of varying sizes happen whenever lava enters much colder seawater.
While some explosions are too small to see, when conditions are just right, large explosions send molten rock and debris high into the air, according to USGS geologist Janet Babb.
Shane Turpin, the owner and captain of the vessel that was hit, said he never saw the explosion that rained molten rock down on top of his boat.
He and his tour group had been in the area for about 20 minutes making passes of the ocean entry about 500 yards offshore, Turpin said.
He didn't observe "any major explosions," so he navigated his vessel closer, to about 250 yards away from the lava.
"As we were exiting the zone, all of a sudden everything around us exploded," he said. "It was everywhere."
Hawaii’s Kilauea volcano continues to spew deadly river of lava from fissure
Turpin said he had no idea just how big the blast was until he saw video of the event later on shore, adding: "It was immense... I had no idea. We didn't see it."
He said he had visited one woman who sustained serious injuries in the hospital, adding: "They're unbelievable people."
Officials have warned of the danger of getting close to lava entering the ocean, saying the interaction can create clouds of acid and fine glass. Despite the hazards, several companies operate such tours.
The Coast Guard said tour vessels have operated in the area going back at least 20 years.
The US Coast Guard created safety zone where lava flows into the ocean off the Big Island, prohibiting vessels from getting closer than 984ft.
But the agency allows experienced boat operators to apply for a special license to get up to 164 feet from where lava sizzles into the sea.
Kilauea volcano has destroyed more than 700 homes since it entered a new phase in May, but the only serious injury over the past two months was to a man who was hit by flying lava that broke his leg.
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