A marathon swim, but failure for the man hoping to become the oldest person to swim Cook Strait.

Sixty-year-old Mike Bodger spent nearly nine and a half hours yesterday attempting to become the oldest person to cross the notoriously difficult piece of water. He gave up nearly six kilometres from the North Island.

Mr Bodger says the sea was calm during the first half of the swim but then big waves struck and a strong northerly wind pushed him sideways. He says he actually swam 28 kilometres, which is about five kilometres more than a direct crossing would have been.

Mr Bodger does not plan to make another attempt as it is a huge commitment and too dependent on the weather.