A monster wave towering more than 60 feet high – the biggest ever recorded – swept the North Atlantic four years ago, virtually undetected because it didn't sink any ships or slam into any shores.
Data from an automated buoy showed the giant wave rose at 0600 GMT on Feb. 4, 2013, at a remote spot between Britain and Iceland, said the World Meteorological Organization.
The data was scrutinized by the UN's weather agency and on Tuesday it revealed the existence of behemoth wave that rose 19 metres (62.3 feet), reported Agence France-Presse.
"This is the first time we have ever measured a wave of 19 meters. It is a remarkable record," said WMO deputy chief Wenjian Zhang.
Taller than a six-story building, the mighty wave occurred after a "very strong" cold front had barreled through the area, producing winds up of 43.8 knots (50.4 miles per hour).
The previous record height for a wave was 18.3 meters, notched up in December 2007, also in the North Atlantic.
Automated buoys are vital tools for oceanographers, sending back data on sea currents, temperatures and swells for seafarers, climate researchers and others.
“We need high quality and extensive ocean records to help in our understanding of weather/ocean interactions,” said Zhang.
“Despite the huge strides in satellite technology, the sustained observations and data records from moored and drifting buoys and ships still play a major role in this respect."
The North Atlantic, from the Grand Banks underwater plateau off Canada to south of Iceland and the west of Britain, is the world's biggest breeding ground for giant waves.
At wintertime, wind circulation and atmospheric pressure cause intense extratropical storms, often dubbed "bombs," the WMO said.
The height of a wave is defined as the distance from the crest of one wave to the trough of the next.
The UN agency occasionally reveals quirky weather-related milestones, like its September finding that an August 2012 lightning flash in France was the longest-lasting bolt ever recorded.