The waves crashed in the dark — and without warning.

At least 222 people in Indonesia are dead from a massive tsunami that was spurred by a volcanic eruption and worsened by a full-moon tide— and struck during the region’s peak holiday season, officials said Sunday.

Nearly 850 others were injured when up to 20-foot-tall waves battered the shores of the islands of Java and Sumatra in the Sunda Strait, smashing houses, hotels and other beachside buildings around 9:30 p.m. Saturday.

“I was afraid I would die,” said Azki Kurniawan, a 16-year-old boy in Java. “I cried in fear … ‘This is a tsunami?’”

Moments before the swell struck him, Kurniawan had been in the lobby of the Patra Comfort Hotel when people burst inside shouting, “Sea water rising!”

He said he ran to the parking lot to grab his motorbike — but the area was already flooded.

“Suddenly, a … wave hit me,” Kurniawan said. “I was thrown into the fence of a building about [100 feet] from the beach and held onto the fence as strong as I could, trying to resist the water, which felt like it would drag me back into the sea.”

The teen was one of throngs of residents who were confused because they hadn’t felt the tremors of an earthquake beforehand, which typically serve as an unofficial warning of a potential tsunami.

Earthquakes also trigger official warnings through alert systems.

But Saturday’s deadly wave was the result of “an undersea landslide resulting from volcanic activity,” so the alert system wasn’t triggered.

Mother Nature didn’t help — the region’s high tides caused by the full moon fueled the tsunami, said Sutopo Purwo Nugroho, a spokesman for the National Disaster Mitigation Agency.

The Anak Krakatau volcano — which sits roughly halfway between the impacted islands — was the source of the rocky landslide that pushed up the water, creating the massive waves, scientists said.

The volcano has been spewing ash and lava since June and erupted just about 30 minutes before the tsunami, leading to the partial collapse of its slope and spurring the waves.

“This is like suddenly dropping a bag of sand in a tub filled with water,” said Ben van der Pluijm, an earthquake geologist and a professor in the University of Michigan.

Stunning video footage caught the moment a wave came crashing down on the stage of a rock band performing in Java.

Java shop owner Rudi Herdiansyah described his own stretch of beach as being quiet — until he heard a “very loud noise from the sea.”

A wall of water rammed into his small beachside store, and he was dragged away by a powerful wave.

“I tried to get hold of anything to help me survive. I hid away and clung onto a bench to be safe,” Herdiansyah said.

Oystein Lund Andersen, a Norwegian volcano photographer, told the BBC, “There was no activity at all” on the ocean before a sudden swell appeared.

“It was just dark out there. … And suddenly I saw this wave coming, and I had to run,” he said.

Another witness, Asep Perangkat, told Agence France-Presse he was with his family on Carita beach in Java when a wave hit, carving a devastating path.

“Cars were dragged about” 32 feet, Perangkat said. “Buildings on the edge of the beach were destroyed, trees and electricity poles fell to the ground. All the residents that are safe ran to the forest.”

More than 500 houses, nine hotels, 60 restaurants and 350 boats are known to have been damaged during what is the region’s peak holiday season, the disaster management agency said.

“Everything has been destroyed, and we don’t have the money to rebuild,” said a woman named Rani, who ran a beachside stall on Java that was crushed by a wave.

Chunks of concrete, pieces of wood and other debris littered the beach getaways popular with tourists and Jakarta residents, turning them into ghost towns.

In the city of Bandar Lampung in southern Sumatra, hundreds of residents took refuge at the governor’s office.

Body bags dotted the area, with weeping relatives identifying the dead.

Dozens of people are still missing, and the death toll could increase, officials said.

Rescue efforts continued as night fell Sunday, but some workers and ambulances had trouble reaching affected areas because some roads were still blocked by debris.

Indonesia’s president, Joko Widodo, expressed his sorrow for the victims and urged the “people who are left” to be patient with recovery efforts.

At the Vatican, Pope Francis prayed for those who perished and the now-homeless, saying the victims were “struck by violent natural calamities.”

President Trump also expressed his support.

“We are praying for recovery and healing. America is with you!” he tweeted.

Officials warned people to stay away from the coast for fear that more volcanic eruptions could cause another tsunami.

The volcano — whose named means “Child of Krakatoa” — was formed over the years after the 1883 eruption of the Krakatoa volcano.

That disaster killed more than 30,000 people in one of the largest, most devastating eruptions in history.

A high-tide warning will remain in place until Dec. 25.

A double quake-and-tsunami killed more than 2,000 people on Sulawesi island in September.

With Post Wires