Penrhyn's turquoise 280-square-km lagoon is so wide that you can just see the roof of the church at Tautua from Omoka, the administrative center. The motu at the far end of the lagoon are too far away to be seen.
The lagoon is thick with sharks, mostly innocuous black-tips; only the black shark is dangerous. The islanders ignore them as they dive for oysters. Now pearl farming is developing with 150,000 cultured oysters already hanging on racks in the lagoon and an oyster hatchery near Omoka is adding to their numbers every day.
Penrhyn was named for the British ship Lady Penrhyn, which arrived in 1788, although one of the Polynesian names is Tongareva. The legendary hero Vatea fished Penrhyn up from the sea using a hook baited with a piece of flesh from his own thigh.
In 1863 four native missionaries on Penrhyn were tricked into recruiting their congregation for Peruvian slavers at $5 a head and sailed with them to Callao as overseers for $100 a month in the hope of obtaining enough money to build a new church! The blackbirders dubbed Penrhyn the "Island of the Four Evangelists" in gratitude. This tragedy wiped out the chiefly line and Penrhyn is today the only Cook Island without an ariki. Remnants of old graves and villages abandoned after the raid can still be seen on the motu, and the ruins of an unfinished church crumble away at Akasusu.
The island has a good natural harbor, one of the few in the Cook Islands, and vessels can enter the lagoon through Taruia Passage, just above Omoka, to tie up at Omoka wharf. In 1995 a fuel depot opened here for ships patrolling the fisheries zones of the Cook Islands and Kiribati (Penrhyn is closer to Christmas Island than it is to Rarotonga). Development plans by the Rarotonga government have been resisted as various local factions vie for influence. Fine pandanus rito hats and mother-of-pearl shell jewelry are made on Penrhyn and visiting yachties can trade kitchen- and tableware, dry cell batteries, rope, and small anchors for crafts and pearls.
American forces occupied Penrhyn during 1942-1946 and built a giant airfield at the south end of Omoka about five km from the present village. Aluminum from the wreck of a four-engined WWII Liberator bomber named Go-Gettin' Gal was used by the islanders to make combs and not much is left other than three engines near Warwick Latham's house and a fourth engine in the village. Concrete building foundations from the war and from a base camp that supported British and American atmospheric nuclear tests on Christmas Island in the early 1960s can be seen. The waters around the atoll are a rich fishing ground, and Penrhyn is used as a base for patrol boats and planes monitoring the activities of foreign fishing fleets.
Air Rarotonga flies once a week from Rarotonga (1,365 km) to this most northerly Cook island. The airfare is high partly because of an exorbitant landing fee levied by the island council. Several local residents run guest houses in the center of Omoka village to accommodate visitors. House rentals are also possible and Air Rarotonga can help with the arrangements.