As the earthquake struck, a Christchurch lifeguard could only watch in horror as a cliff began to collapse just above the youngsters he was supervising - including his son.
Craig Jamieson, the Taylors Mistake Life Saving Club patrol captain, was looking after 12-year-old son William and four other rookie lifeguards as they took part in a cliff-jump exercise.
Mr Jamieson was in a rescue boat in the sea below when he realised that what he thought was maybe a dolphin bumping his craft was in fact an earthquake.
"I'm in a boat that's sitting in water and it's completely out of control, to a point that I'm nearly falling out of it. That's how much movement there was in the sea," Mr Jamieson said.
"I can hear the noise, then I look up and I can see the cliffside falling over these guys. There's just this huge noise."