The minor market at the 200 strong party became terrible after they faced the police.
Nine arrests were made at a party on Auckland's north coast earlier this month.
The City-owned council, at Takapuna Central, was contracted to have no alcohol in the field.
"The police are confronted with up to 200 innocent people, many minors who have involved the police," the police said in a statement.
"Nine people were arrested, and the Takapune CBD area was closed for more than an hour after the police tried to restore order."
Drinking alcohol in less than 18 years at a pre-planned event launched an investigation by the police and councils of charges likely within the Law on Sales of Spirits.
The police used the illegal party as an opportunity to remind parents and carers of their legal obligations during the event.
"Remember that you are responsible not only for your child, but for the well-being of every child or young person who attends that event."
Basics of alcohol from the police NZ:
• Parents or guardians:
• It is necessary to be responsible for how many people drink from 18 years of age.
Supervisory amount and what they drink.
• Make sure that the under 18 years of age do not drink too much, eat food, drink water and are physically and emotionally safe.
• If you watch movies or drink with your friends above, they are not considered as surveillance or responsibility.
• If you, as a parent or guardian, are satisfied with your younger than 18 years of age to go to a party with alcohol, then you must give permission to adults who will be responsible and responsible for your child on that party.
• Speaking directly to that person and asking a question is a good indicator of the type of party you allow to attend.
• As an adult, if you organize a party for your younger than 18 years of age or you are under 18 years of age, you are entitled to a bribe if that party becomes out of control and under 18 is drunk.
• As an adult at a party it does not matter if the younger than 18 years of age brought their own alcohol or gave it to you, you can still charge.
• Supplying alcohol to younger than 18 years old is not your fault.
• If he is in charge of a party in which he is drinking at least 18 years of age, he is a misdemeanor.