Sir Peter, who has a home outside Masterton, said he and his fellow producers were deeply shocked and saddened to learn of Hopkins' death, Radio New Zealand reported.
He said many actors, directors, production and post-production crew who were lucky enough to work with Mr Hopkins would miss him deeply.
Under Mr Hopkins' guidance, New Zealand became recognised as one of the leading hubs of post-production sound in the world, Sir Peter said.
Mr Hopkins was genuine, caring and warm-hearted, with a great sense of humour.
Their collaboration dated from Braindead in 1992.
Film editor and producer Jamie Selkirk, who also won an Oscar for his work on Lord of the Rings, said he employed Mr Hopkins when he was a school leaver to run errands in his production company.
But he quickly proved his aptitude in the pioneering area of cinematic sound.
Greytown man Bruce Slater, who was an experienced boatie and was called to the river about 4pm on Sunday, said the group were "so unlucky".
"If they were half an hour later they wouldn't have launched the boat because it came down as a wave of water," Mr Slater said.
The 64-year-old farmer, who is an experienced jet boater, said he and his son, Andrew, launched the boat from Kuratawhiti Street, near the Waiohine Bridge.
The pair picked up Mr Hopkins' wife about 12km along the river.
Mr Slater said when she was rescued, the other man in the rafting group had managed to escape the river but Mr Hopkins had already been picked up by the Westpac Rescue Helicopter.
Mr Hopkins and Ethan Van der Ryn won an Oscar for their sound editing on King Kong in 2006. The pair also won a best sound editing Oscar on Lord of the Rings: The Two Towers in 2003.
Mr Hopkins was nominated for a Golden Globe for his work on the Transformers movie, but did not win. He had a career in sound editing for more than 60 movies and television shows, spanning four decades.
Mr Hopkins worked on all three Lord of the Rings movies, as well as Kung Fu Panda, and Dreamgirls. He also was sound editor on Sir Peter's 1994 film, Heavenly Creatures.
APNZ