At 8am on 3rd October 1952, Britain detonated its first atom bomb
aboard the HMS Plym, which was anchored offshore of Trimouille, one of
the Montebello Islands, situated approximately 75 nautical miles north
of Onslow, off the West Australian coast.
The 25kilogram nuclear fission device vaporised the Plym and its
surroundings in a test codenamed Operation Hurricane. It was the
beginning of a series of 29 British nuclear tests in Australia and
several South Pacific islands from 1952 to 1958, in which more than
22,000 British, 14,000 Australian and 500 New Zealand servicemen were
Situated approximately 75 nautical miles north of Onslow and 20 km
north of Barrow Island off the Western Australian coast, the islands
were named by the French navigator Nicolas Baudin in August 1801.
Baudin was evidently "discouraged by the seeming barrenness of the
country, the scarcity of fresh water and the hostility of the blacks",
so kept to the sea and did little else than survey the coast line and
islands. Before he left, however, he named the islands after the battle
of Montebello, where the victorious French general Jean Lannes
(1769-1809), Marshall of France and later the Duke of Montebello,
defeated the Austrians in 1800.
The flat limestone islands range in size from Hermite, the largest,
at about 1,000 ha, to several small islets and rocks of less than one
hectare. They are the remnants of an old coastal landform and have been
separated from the mainland for more than 8000 years. No evidence has
been found of Aboriginal occupation of the islands since that
separation, although they probably lived there before.
The earliest known European use of the islands was in 1622, when one
of Australia's first recorded shipwrecks, that of the Trial took place
just west of the Montebellos. The survivors of the wreck spent seven
days on the northern islands before setting forth for the East Indies.
Only 30 could sail with the captain in the lifeboat, the rest were left
to their fate on the wrecked ship. Other early navigators, Baudin in
1801, King in 1818 and Stokes in 1840 had less eventful voyages.
The development of the pearling industry along the north west coast
in the late 19th Century formed the next exciting chapter in the
history of the Montebellos. The pearlers who fished the waters and
camped on the islands are probably responsible for the introduction of
the cat and the black rat who in turn are accountable for the
extinction of the golden bandicoot and spectacled hare wallaby.
In 1952 the British joined the exclusive nuclear club by detonating
their first atomic weapon on H.M.S. Plym, moored in Main Bay, close to
Trimouille Island. Further atomic bombs were exploded on Trimouille and
Alpha Islands. Many relics of the infrastructure and detonation remain
today. Regular monitoring of radiation levels shows that, with the
exception of ground zero sites (the exact places the bombs were
detonated) radiation has dropped below levels considered dangerous to
Today the waters around the Montebello Islands provide excellent
sheltered anchorages for vessels of all sizes and are frequently
visited during the winter months by numerous boats. Some islands have
been zoned for recreation, while others have been reserved for the
protection of nesting seabirds and turtles. Montebello Island Safaris
offers tours of the islands from their base in Onslow.