St Peter and St Paul Rocks, Atlantic Ocean

It is not unusual to find groups of rocky islands close to a coastline, but stuck out in the middle of an ocean? That is where you will find the St Peter and St Paul Rocks – in the Atlantic Ocean about 590 miles from northeast Brazil and 1,100 miles from west Africa.

They are 15 small islands that rise to no more than 60 feet above the sea. The total land area is about 160,000 square feet. They are uninhabited, although the Brazilian Navy has established a scientific station and lighthouse on the largest island.

The name comes from the event that led to their discovery in 1511. A Portuguese nobleman, Garcia de Noronha, was in charge of a fleet of six caravels on a voyage to India. One of the caravels, “St Peter”, crashed against a rock at night in the middle of the ocean, and the crew had to be rescued by the crew of another caravel, “St Paul”. 

The St Peter and St Paul Rocks, despite their apparent lack of importance, are extremely interesting from a geological point of view. They are the very top of an undersea mountain that only just breaks the surface. The technical term for the sort of feature they represent is “megamullion”, this being a ridge that runs at right-angles to a mid-ocean ridge, which in turn marks the point where two tectonic plates are moving apart and allowing new ocean crust to form. The Rocks are the world’s highest megamullion (at 12,000 feet), being composed of mantle rock, and are not an undersea volcano that has reached the surface.

The Rocks were visited by Charles Darwin when on board HMS Beagle in 1832. He noted that they had very little to offer in the way of wildlife, and that he not been able to find a single plant anywhere on the islands. He did find two birds, a moth, a crab and some spiders, but that was about it. 

Had Darwin stayed longer, he might have noted the relative richness of the tidal pools, which support sea slugs, shrimps and lobsters. The islands are visited by many migrating seabirds, and the seas surrounding them are populated by some 75 species of fish, including deep-water eels, sharks, and five – including the St Paul’s Gregory – that are found nowhere else.

This is a place that very few people visit, or are ever likely to.

© John Welford

Gough and Inaccessible Islands

These two small and remote islands in the South Atlantic Ocean have UNESCO World Heritage status because they are important nature reserves. 

They are volcanic islands that are highly attractive to wildlife but of no commercial interest, which is just as well for the wildlife. They are therefore uninhabited, except for a small weather station on Gough Island.

Gough Island (pictured) lies between the British territory of Tristan da Cunha and South Africa, being a dependency of the former. It is around 35 square miles in size, just over 8 miles long and 4 miles wide. It has been described as the world’s most important seabird colony with some fifty species of bird found there.  

It is the breeding ground for nearly half the world’s population of rockhopper penguins, it has about three million pairs of great shearwaters, 2,000 pairs of wandering albatrosses, and the world’s last remaining southern giant petrels, now reduced to no more than 150 pairs. 

Inaccessible Island (just under five and a half square miles in size) is part of the Tristan da Cunha island group. Its name may not be strictly accurate, but access is highly restricted so that the wildlife can remain undisturbed. It is one of the few ocean islands in the temperate zone to which no non-native mammals have been introduced. It has two bird, eight plant and ten (or more) invertebrate species that are endemic to the island.

© John Welford