20,000 Leagues Under the Sea is a graphic adventure created by Coktel Vision. It is a videogame adaptation of the famous sci-fi novel by Jules Verne, written in 1870.
The game was released in 1988 for Atari ST, Amiga, MS-DOS, and Amstrad CPC. This point-and-click adventure didn't age very well, but it's still a fascinating attempt at converting the book that is considered the precursor of the steampunk genre.