The Scilly Isles are located southwest of Cornwall’s Land’s End in the Atlantic Ocean. The islands were more extensive before the end of the last Ice Age and their inundation following the melting of the glaciers undoubtedly produced numerous legends in the region of sunken cities and lost civilisations. Apparently, there was once a paved causeway joining some of the islands and according to an 18th-century report, it was then under 8 feet of water. Even earlier in the 3rd century AD, Solinus referred to the Scillies in the singular as insulam Siluram.
O.G.S. Crawford, who was the first Archaeology Officer with the British Ordnance Survey, was also the founder in 1927 of Antiquity which continues today. In its first edition(c) he wrote of the earlier Scillies as a single landmass and its relationship to the legend of Lyonesse(b).
Some writers have identified the Scillies as the Cassiterides (Isles of Tin) referred to by Pliny the Elder. However, there are no known tin deposits on the islands, although it is possible that before the ocean levels rose ore deposits were accessible, similar to those in nearby Devon and Cornwall, but this inundation probably occurred before the technology existed to exploit its use.
In more recent times the Russian Scientist Viatcheslav Koudriavtsev was convinced that Atlantis was located on the Celtic Shelf near the Scilly Isles. He specifically identified an underwater feature known as the Little Sole Bank, whose highest point is just 75 metres beneath the ocean’s surface. He had been promoting his theory since 1995 and eventually obtained official government permission to carry out explorations in the area, but he was unable to raise the necessary funds to carry out the operation.
In 2009, excavations on St. Agnes in the Scillies revealed a remarkable Bronze Age pottery sherd which seems to depict the earliest know image of a sailing boat ever found in the United Kingdom(a).
In 1651, the Netherlands declared war on the Scillies, a little detail that was forgotten until 1986, when a peace treaty was finally signed(d) !
(c) https://www.cambridge.org/core/journals/antiquity/article/lyonesse/37725F1992B3D4ADF36561E144227F11 (Jan. 2019 access restricted)