"We're finding cash that we would not have found before. That's not just moving cash in suitcases, that's cash being smuggled on the body as well."
The movement of undeclared cash is of particular concern because its presence at borders often suggests it has been or will be used for illegal activities.
"Customs is interested in movements of large sums of cash across the border. Money laundering is how criminals hide the illegal origins of their money. Movement of cash can and has been linked to money laundering and organised crime; this is why we treat the matter so seriously," a customs spokeswoman said.
"It's not illegal to carry large sums of cash but it must be declared so we can verify that the money is legitimate and for legitimate purposes."
Under the Anti-Money Laundering and Countering Financing of Terrorism Act 2009, those caught sneaking money in or out of the country are liable for "a term of imprisonment of not more than three months, a fine up to $10,000, or both".
False cash declarations or "non-reporting of cash" may result in the money being forfeited and seized by the authorities, customs says.
The cash dogs don't sniff out only money, however. Most of them are multi-talented. Nationally, there are 13 operational detector dog teams, consisting of a dog and a handler, says customs communications group manager Katie Mathison.
"Two of the detector dogs are trained to detect explosives, four dogs are trained to detect drugs, and seven dogs are trained to detect both drugs and cash.
"The detector dog teams are based in Auckland, Christchurch and Wellington, though they can be deployed to other locations around New Zealand as required.
"All the current operational detector dogs are Labrador retrievers from the Australian Customs Breeding programme in Melbourne."
The dogs work screening passengers, aircraft, baggage and cargo at international airports; investigating letters and packages at Auckland International Mail Centre; sorting through shipping containers, fishing vessels, cruise ships and yachts; and helping with search warrants.
Flame hot on scent with her drug training
Auckland Airport's latest sniffer dog, Flame, really is bright eyed and bushy tailed. She is the newest kid on the block in Customs, jumping the ditch from Melbourne four weeks ago.
The black Labrador has two months of training to go before she's a fully qualified sniffer dog.
Customs detector dog programme manager David Huff said she was doing really well and enjoyed her training. "All it is to the dog is a game ... it must do it because it wants to."
Using "play" as a treat, Mr Huff said handlers began training by soaking articles, such as a rolled up towel, in the scent of a drug and using it to play with the dog.
They eventually hid the scent-soaked objects in long grass, then boxes, and finally in suitcases - getting the dogs to sit passively as soon as they had the scent. "Then we start using distractions like coffee, tea, cans of fish, dog food and they have to find the drug amongst it."
Flame was up to the suitcase stage.
"We're really happy with her."
Once she was working, Flame would be doing eight-hour shifts every day, working at the airport or in cargo, Mr Huff said.
Smell of success
• $3.3 million in cash has been smelled out at Auckland Airport's international terminal.
• 2100 hidden caches of drugs at airports, mail centres and ports have also been found.
• $150,000 some of the largest hauls.
• 13 operational customs detector dog teams are working currently.
- additional reporting Holly Dove