Dion Reynolds and Jessica O'Connor have been found alive, after they did not return from a tramp through the Kahurangi National Park 18 days ago.

The pair sustained only minor injuries but an ambulance had met a helicopter to take them to Nelson hospital.

Search and rescue sergeant Malcolm York says civilian aircrafts using a search radar found the two trampers.

"They saw a single puff of smoke come out of the bush.

They went in and got this amazing glimpse through a very high canapy, of two very happy looking people."

Mr York says the bush was very thick and tall, and the helicopter rotor cut through the top of the trees.