A man commented that the boy had "light blondie hair, yellow top or raincoat, red gumboots".
The New Zealand Lost Pet Register is one of the first to pay tribute to the boy.
"Our hearts are absolutely broken for Max and his family as the news is in that sadly his body has been found.
"We also want to give our condolences to the rescue teams and members of the public that were involved in the search and recovery of this beautiful young man. RIP sweet heart, you will never be forgotten."
Piha Surf Life Saving Club said they weren't involved in the search and could not comment.
The matter will be referred to the Coroner.
Next of kin are still being notified.