"Where they were it was just pretty much solid white water."
"I couldn't get the boat anywhere near the rocks. Matt had to swim in and grab them and swim them back out."
But Mr Craig said the divers wouldn't leave behind their gear, so his son first swam their equipment through the swell to the IRB.
"They wouldn't get off the rock without their diving gear so Matt swam it out to me first, at which point I said he should have just let it sink," he said.
He said one of the divers was in good shape and able to swim to the boat himself, but the other was "in a sort of distressed state, and he was a big fella".
"Matt swam him out and we got him into the boat after a bit of effort."
Both divers were then taken to the Coastguard boat waiting about 300m off the rocks, and shining a searchlight to assist the 9pm rescue.
Mr Craig said he didn't have much opportunity to speak to the divers after their rescue.
"They were just pretty happy to get off the rock and pretty happy to get on some dry land," he said.
He said it could have been possible to swim into shore from the position where the divers were stranded, but "the big guy, he was stuffed. He was had it."
Police said the diver was taken to hospital suffering from hypothermia.
Mr Craig, a builder, said his son had been involved in lifesaving since a young age and was a strong swimmer.
