Skydive Auckland director Tony Green said staff could not find any broken bones, but it was obvious he had suffered serious head injuries.
A Civil Aviation Authority spokeswoman said yesterday that the incident had not been reported.
"It is a reportable accident, and the CAA will now approach skydiving operations at Parakai for details."
The airfield were conducting their own inquiries.
The man was in a serious but stable condition in Auckland City Hospital yesterday.
Parakai Airfield manager Simon Lockie said what happened to the man as he landed was a mystery.
"He was well experienced. He had quite a few thousand jumps under his belt."
A spokeswoman for the Auckland Westpac Rescue Helicopter said the man was in a critical condition when paramedics arrived.
Paramedics worked frantically to stabilise the man before they could airlift him to hospital.
He was admitted in a serious condition and there were concerns about internal and brain injuries.
Helicopter crewman Mark Cannell said the man landed beside trees.
"He was lucky to have not come down in amongst that lot," he said. "It sounded like he had come down wrong and contacted the ground very hard."
Mr Green said there were always risks with extreme sports, and those who participated knew the dangers.
"The investigation will show that he had an accident. The only way to completely stop these sorts of accidents happening is to stop the activity," he said. "It's very unfortunate, but hopefully he'll be back in the sky with us again soon."
