"Mike was a very genuine, caring and warm-hearted guy with a great sense of humor," Jackson said.
A native New Zealander, Hopkins shared Oscars with sound editing partner Ethan Van der Ryn in 2006 for "King Kong" and in 2003 for "The Lord of the Rings: The Two Towers." They also were nominated for 2007's "Transformers."
Hopkins also was sound editor on the two other "Rings" films and had worked on earlier Jackson movies including "Heavenly Creatures" and "The Frighteners."
The Herald reported a family celebration of Hopkins' life was planned on Thursday.
A river contractor, Bruce Slater, and his son used a jet boat to rescue Hopkins' wife. Nicci Hopkins had been in the Waiohine River two hours and was clinging to a ledge in a narrow part of the gorge too dangerous for bigger boats or a helicopter.
"If they'd been half an hour earlier, they would have been clear of the gorge," he said. And a half hour later, the water levels would have been noticeably dangerous before the rafters launched, Slater said.