Some 24 lifeguards and eight coastguards took part in the simulation, which centred around a supposed collision between a boat and a jet ski, off rocks at the southern end of Omaha Beach.
Drama students from Mahurangi College played the victims, complete with realistic-looking wounds and symptoms. Lifeguards launched four IRBs to treat and transport them, and coastguard vessel Kawau Rescue coordinated a sea search.
Meanwhile, along the coast at Mangawhai Heads, more than a dozen lifeguards took part in their own start of season refresher, completing various rescue, fitness and first aid exercises.
Lifeguards will be on patrol at both beaches every weekend and public holiday from now until the end of March.