Police have seized more than half a million dollars' worth of drugs, along with hundreds of thousands of dollars in cash in Auckland.
The alleged offenders purchased the drugs using the digital currency bitcoin, and the drugs were then imported through international mail.
The "hardcore" drugs intercepted in 'Operation Tiger' over the last six months included methamphetamine, LSD, fentanyl and GBL.
Thirteen people, ranging from 19 to 59 years old, were arrested and have since appeared in the Waitakere, North Shore or Auckland District Courts on a total of 79 charges.
"Buyers may think small quantities of drugs don't matter and Customs won't do anything, but every seizure helps us and our partners build the intelligence picture, so it's not a matter of if they are caught, it's when," says customs intelligence Manager, Wei-Jiat Tan.
"It is only a matter of time before police or Customs will come knocking on your door and you will be facing serious drugs charges," added Detective Sergeant Williams.
The investigation came after results from a previous operation in 2016, which found that people who commonly engaged in the online purchasing of illicit drugs were often young people who did not typically have a record of previous drug offending.