Loud explosions heard at Muriwai beach on Friday evening was the Defence Force detonating a "small cylindrical object".
Multiple residents heard loud noises about 9pm, not long after a water rescue took place at the surf beach, where a rescue helicopter was dispatched.
Police confirmed the incidents were unrelated and that a controlled detonation of an unidentified object took place.
A police spokesman said police were called in to help the Defence Force at 3pm after a "small cylindrical object" was found at Takapuna, on Auckland's North Shore.
Police couldn't be specific about what the object was.