A passenger died and four others were injured after a large, unexpected wave hit a cruise ship travelling toward a popular launching point for expeditions to Antarctica, Viking Cruises said.

The ship, the Viking Polaris, was struck by a “rogue wave” on Tuesday at 10.40pm local time while travelling toward Ushuaia, Argentina, which is on the southern tip of South America, Viking Cruises said in a statement.

Viking Cruises did not say how the passenger was killed or provide the passenger’s name. The four passengers who were injured were treated by onboard medical staff and had non-life-threatening injuries, Viking Cruises said.

A State Department official said that a US citizen died and that the department was offering consular assistance to the person’s family.

Rogue waves are unpredictable, typically twice the size of surrounding waves and often come from a different direction than the surrounding wind and waves, according to the National Oceanic and Atmospheric Administration.

Scientists are trying to figure out how and when these uncommon waves form. Ann Mah, of Topeka, Kansas, told the news station WIBW that she and her husband were on the ship when it was hit by the wave and that it was “just like your whole house got shook really hard”. “I mean, it was just a thud,” Mah said.

The Viking Polaris was launched this year and was designed for travel to remote destinations such as the Antarctic Peninsula. The ship is 665 feet long and can carry 378 passengers and 256 crew members.

The ship sustained “limited damage” from the wave and arrived in Ushuaia the day after it was struck, Viking Cruises said. The cruise company cancelled the Viking Polaris’s next scheduled trip, a 13-day cruise to the Antarctic Peninsula.

“We are investigating the facts surrounding this incident and will offer our support to the relevant authorities,” the company said.

New York Times News Service