A Waikato pig hunter took a photograph of his dogs bailing up a pig on the other side of lake, just moments before he drowned while trying to swim across and help them, a coroner's findings have revealed.

Kevin Hayward, 41, from Ohaupo, drowned in Lake Waipapa, on the Waikato River near Mangakino, in July during a pig hunting trip.

In findings into Mr Hayward's death released on Thursday, coroner Tim Scott ruled he died from drowning, complicated by hypothermia.

In July, authorities were alerted Mr Hayward may have got into trouble when one of his five dogs was spotted hanging around his car, parked on the eastern side of the lake.

Searchers found another of his dogs on the western side of the lake. Using that dog's tracking collar they were able to find the spot where Mr Hayward entered the water.

There they found his shotgun and a camera. His clothing was found in the water.

Divers retrieved Mr Hayward's body from the bottom of the lake in about 14m of water.

His digital camera contained a photograph taken from the point where he had taken his clothes off, and when enlarged, the picture his dogs could be seen bailing a pig on the opposite side of the lake - about 100m away.

It was clear Mr Hayward had tried to swim across the lake to help the dogs kill the pig, Mr Scott said.