More than 20 people are facing charges after a beach hop event at Whangamatā on the Coromandel Peninsula this weekend.
The five-day annual event that brings together rock 'n'roll fans as well as classic car and hot rod enthusiasts, is due to finish today.
Police said the majority of those who attended had behaved well so far, however, last night they had to deal with some who became intoxicated.
Twelve people were arrested for various street offences, including fighting in a public place. A large number of alcohol infringement notices were issued for breaches of the liquor ban, a spokesperson said in a statement.
Over the course of the weekend 13 drivers were caught behind the wheel with excess breath alcohol.
"This is unacceptable and disappointing for police.
"Waikato has seen its fair share of fatalities on the road over the course of this year and we know that intoxication increases the chance of causing harm on the road."
As the holiday period approached, it was a timely reminder for drivers to remember the responsibility they had on the road, the spokesperon said.
Police intended to continue to target drink drivers and encouraged anyone who has been drinking to consider not only their safety, but that of other motorists too, and plan ahead by organising a sober driver.