What exactly is a 'rogue' wave?
It's an unusually large and spontaneous wave that occurs far out at sea. That means they are at best difficult and at worst impossible to anticipate. They can be more than double the size of the largest one-third of the waves measured. For example...if the heights of the largest third of waves sampled average 25 feet, a rogue wave could be 50 feet...or higher. For the record, some waves have been measured in excess of 100 feet!