Steven Morris in The Guardian:
A British explorer has discovered an abandoned 19th-century submarine which may have been the inspiration for Captain Nemo’s vessel Nautilus in Jules Verne’s 20,000 Leagues Under the Sea.
Colonel John Blashford-Snell found the cast-iron submarine, named Explorer, half-submerged in three metres of water off the coast of Panama.
Like Nautilus, the craft is cigar-shaped and has a lock-out system, which allows submariners to leave, collect items from the seabed and then return to the vessel.
It was built in 1864, five years before Verne’s classic adventure story was published, and it is thought that the French writer would have read about the sub’s specifications.
More here.