MARGARET RIVER, Australia (Reuters) - The waves have been nicknamed Cyclops, Jaws and Dungeons and are the new life-and-death playground for a unique breed of surfers who ride gargantuan ocean waves as big as a seven storey building. Australian surfer Alex Cater, 25, has been chasing giant waves for the past five years and knows only too well the agony and ecstasy of what they call tow-in surfing, where a surfer is whipped by jet ski into giant waves bigger than most tsunamis. "If you don't have a bit of fear then you shouldn't be out there," said Cater. "When...