A police spokeswoman confirmed they were called by a member of the public just before 7am after the body was found between Lion Rock and the mid-beach toilet block.
She said the body had not been formally identified.
A Piha woman, who did not want to be named, heard about the body while walking her dog at the west Auckland beach this morning.
"There was a bunch of people standing on the beach and a fella ran up to me and said not to go anywhere near them. I didn't see a body at that point, but one of our customers said they saw something under a sheet," she said.
"The police have been around but they obviously don't want to talk about it. The smell out here has been awful the last two days, so something's happened. We were hoping it was a seal.
"I haven't heard anything else, but maybe it was that one that went missing, it's been a long time."
Auckland nurse Kim Bambus is believed to be the last person to have gone missing at Piha.
The 21-year-old told friends she was going for a run at the beach in March but never returned. An extensive search found no trace of Bambus.
