A teacher who was spear fishing in the waters of Australia was eaten alive by a huge great white shark, an inquest has heard.

Sam Kellett was devoured by the five-metre man-eater off the Yorke Peninsula coastline as his friends watched on in horror.

Witnesses at the scene said that the ocean was coloured red with the 28-year-old’s blood near where he had just been swimming.

His body was never found but police divers discovered Mr Kellet’s spear gun and two lead weights.

The gun had “discernible serrated incisions” consistent with great white shark teeth impressions.

Witness Aaron Whitaker said in a statement: “I turned around [and] saw the tail of a shark come out of the water - and it was thrashing around.

"I put my face under the water to see the shark but I could not see it.

"All of a sudden a shark came out the murky water vertically towards the surface just behind me and almost launched itself out of the water.”

View photos

Other eyewitnesses to the fatal attack also described the moment they saw the shark in the water.

Nicholas Carson said in an affidavit: "I was directly behind the shark so I saw the whole body jump out of the water.

"I think the shark was about 5m long and it was a dark grey colour.

"It looked like a great white shark. It happened so fast.”

Wyatt Raymount added that he saw a shark in the exact position where he last saw Mr Kellett, who was spear fishing with pals at Goldsmith Beach after a fire warning forced them to move from Innes National Park.

Mr Kellett, a teacher at Glenunga International High School, was described as a “wonderful young man” by the principal.

His parents also paid tribute to their son, but refused to blame the shark that killed him.

They said in a statement: "He knew he was a a visitor in their backyard and the last thing he would want is for this shark, or any other, to be hunted down and culled.”

The inquest continues.