Hopkins drowned after the raft he and friends were on in the Waiohine River in the Wellington region capsized on Sunday (30Dec12).
His body was found by a helicopter rescue team. His two companions, a man and a woman, were rescued.
Police Senior Sergeant Carolyn Watson tells TVNZ, ""All three were wearing lifejackets, wetsuits and helmets at the time. We would like to thank all those who assisted in the recovery of Mr Hopkins and the rescue of his companions, particularly the jet boat operator who came to our aid and, at considerable risk to himself, was able to rescue the female.
""Our thoughts are with the family at this difficult time.""
Hopkins had a close working relationship with Peter Jackson, first teaming up with the director as sound designer for the 1992 horror-comedy Braindead.
He also joined Jackson for 2002's The Lord Of The Rings: The Two Towers and 2005's King Kong, and he picked up Academy Awards for Sound Editing along with Ethan Van der Ryn for the blockbusters.
Hopkins was nominated for an Oscar for his work on the first Transformers movie, as well as five British Academy of Film and Television Arts awards during his career.
His other film credits include Public Enemies, Valkyrie, Kung Fu Panda and Dreamgirls.