20,000 leagues under the sea Share definition Flag I do believe it is 20,000 fathoms under the sea. Jules Verne may have perdicted nuclear technology, but he knew nothing about nuatical measurement. 20,000 leagues under the sea by IrishRepublicanArmy December 12, 2003 0 0 Get merch Get the 20,000 leagues under the sea mug. Buy Now — $32.95 See more merch