As part of a project called MaxWave - which was set up to test the rumours - two Esa satellites surveyed the oceans.
During a three week period they detected 10 giant waves, all of which were over 25m (81ft) high.
Over the last two decades more than 200 super-carriers - cargo ships over 200m long - have been lost at sea. Eyewitness reports suggest many were sunk by high and violent walls of water that rose up out of calm seas.
But for years these tales of towering beasts were written off as fantasy; and many marine scientists clung to statistical models stating monstrous deviations from the normal sea state occur once every 1,000 years.
"Two large ships sink every week on average," said Wolfgang Rosenthal, of the GKSS Research Centre in Geesthacht, Germany. "But the cause is never studied to the same detail as an air crash. It simply gets put down to 'bad weather'."
Sailors often whisper of monster waves when ships sink mysteriously but, until now, no one quite believed them.