It is the choice no parent — or spouse — should ever have to make.

When New Zealand woman Vanessa Horton crashed her car into a river near the family home, her husband had to make the excruciating choice between saving her or resucing his son, who was trapped in the sinking car.

Silva Horton, 13, drowned in New Zealand's Whanganui River on Saturday night after the car, in which he was a front-seat passenger, came off the road and cartwheeled down a steep 32 foot bank into the water.

His father, Stacy, arrived from their nearby home in Whanganui, on North Island, less than two minutes after the crash to hear his wife screaming in the darkness and the family Mazda submerged, nose-down, three feet under the surface.

As his wife floundered in the water, Horton tried to dive down to the car to rescue his son, but said he could not reach the teenager.

"I tried to get down and get him but I couldn't, it was just too deep. And Vanessa was going under," Mr Horton told the Dominion Post newspaper.

"I made a call to pull my wife to safety. I looked back and I could see the tail-lights but it was too far and I couldn't get him," he said.

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