About 120 people are taking part a maritime response exercise, Exercise Paihere, on Auckland's Waitemata Harbour.
The exercise runs from Tuesday to Thursday and is being led by Maritime New Zealand.
One of the exercises is a simulated clean-up of oil on a shore and residents near Little Shoal Bay are being warned there will be contractors using light machinery on the beach for training but there will be no actual oil on the beach, and no sand will be removed.
Exercise coordinator Mick Courtnell said the 120 national response team members taking part come from Maritime NZ, councils, industry, Massey University and contracted services.
"Activities during the exercise will include on-water operations using recovery vessels and equipment, simulated oiled shoreline clean-up, oiled wildlife recovery and stabilisation, as well as manned and unmanned aircraft deployment for reconnaissance and intelligence gathering," Mr Courtnell said.
This is the first time all of the functions of the NRT are being brought together.