Sapsford (60) was on a jet-boating and fishing holiday when involved in a accident near the convergence of the Hopkins and Dobson Rivers, at the top of Lake Ohau, Senior Constable Les Andrew said.
The accident happened on Monday afternoon, and Sapsford died as a result of injuries received, Snr Const Andrew confirmed.
He declined to release further details last night, saying only that an autopsy had been carried out yesterday and the death referred to the coroner.
Maritime New Zealand spokesman Ross Henderson confirmed the agency had been advised of the death, and would assist the police investigation if required.
"I can confirm there was an accident involving [Sapsford].
"It's now really a police matter," he said.
Sapsford was a prop who played seven games for the All Blacks on the tour to Argentina in 1976 and also played for New Zealand Universities from 1973-76.
He played 86 games for Otago between 1973 and 1982 and played premier rugby for Pirates, University A and Taieri before retiring in 1985.
Otago Rugby Football Union president and Taieri Rugby Football Club life member John Kelly said Sapsford "was a delightful character" on and off the field and was a strong scrummager when he played for Otago.
"He was a happy character who enjoyed his rugby and being involved with rugby people.
"He brought a lot of experience to the Taieri club when he joined us in 1979 and he also coached briefly at club level."
After the tour to Argentina, Sapsford played for the Harlequins and London New Zealand clubs and had three matches for Middlesex in 1978.
He returned to New Zealand and captained Otago in 1979.
Sapsford operated his dental surgery in Mosgiel for the past 30 years and also had a smaller surgery in Ranfurly.
