Largest and northernmost atoll of the Cook Islands is Penrhyn, also known as Tongareva. Its lagoon, 275 square kilometres in area, dwarfs its surrounding motu, which total only six square kilometres.
At 9º south latitude, Penrhyn is 1,400 kilometres from Rarotonga and 350 kilometres from its nearest neighbours Manihiki and Rakahanga. It’s isolation may have contributed to it being one of the last of the Cook Islands to be set foot upon by Europeans.
Penrhyn's huge lagoon occupies an area greater than the land of all 15 Cook Islands put together. From one side of the lagoon it is just possible to see the tops of long lines of coconut palms, which delineate the motu of the other side. The two villages Omoka and Te Tautua lie on opposite ends of the atoll.
The lagoon is up to 200 metres (600 feet) deep and is teeming with turtles, rays, trevally and sharks. Not surprisingly, Penrhyn offers excellent ocean and lagoon fishing and bonefishing here is said to be on par with Christmas Island – Kiribati, to the north.