A second helicopter was stood down before it arrived at the scene, the spokeswoman said.
The initial search involved six boats, including some from Dart River Adventures, on the water searching while a helicopter was on a sandbank near the wharf.
A fisherman who was at Greenstone when the incident was reported had also taken part in the search.
He was “gobsmacked that anything could happen here,” the fisherman said.
The water near where emergency services were called to was basically waist deep, although there was a drop-off which could catch people out, the fisherman said.
Police have thanked all those that took part in search efforts and provided assistance to whānau as the incident unfolded.