The 14-year-old was killed in a train accident in October 2014.
Those at the marae were also celebrating a family birthday and wedding.
Friends and family have taken to social media to express their disbelief and grief at the sudden loss.
Tiana Kauika paid a heartfelt tribute on her Facebook page saying he would always be special to her.
"R.I.P my bro Mingi. you will always have a special place in my heart. I [will] always love no matter what." (sic)
She said he always made her feel special and they spent many nights on the phone laughing.
Biko Rio posted: "Even though he had no ears sometimes lols but he was a loveable chap did no harm to anyone so yeah R.I.P Mingi."
Kristina Jerry posted: "Rachet news .. resteasycous #MingyUerata #WestKoast."
Police say the dead man was taken to Kawhia and the matter was now with the coroner.
Mr Uerata became the ninth drowning victim since January 1.