Sailors' myth or fact?

Tall waves or tall stories? Throughout the ages sailors have talked about giant, freak waves, waves that seem to get taller with the telling, although there is clear evidence that exceptional seas have caused severe damage to ships and many others have disappeared without trace in suspicious circumstances.

Are they tsunamis, or tidal waves, caused by subterranean volcanoes, are they storm driven, turned into freaks by tidal streams or shallow water? Or is is different wave trains clashing and forming monsters? The UK Met Office has been doing some research into freak waves and the subject is to be featured in the BBC2 Horizon programme Freak Wave on 14 November at 9pm.