The mythology of 20,000 Leagues Under the Sea was enhanced by Disney's 1954 movie, and then expanded by 20,000 Leagues rides at the various Disney properties. The one at Disney World is gone, but created such strong fans that there is more than one website dedicated to it.
For steampunk home decor, however, we're interested in the interior of the Nautilus, ideally in high quality pictures. For our purposes Les Mystères du Nautilus at Disneyland Paris is the best bet.
Dave, the proprietor of the 20kride.com site, has more pictures than you can imagine, and a handful show the industrial Victorian grand future that we all enjoy.
There are more and larger pictures on the original site. Also worth a look are the pictures of the Mysterious Island attraction at DisneySea Tokyo and pictures of the 20,000 Leagues exhibit at DisneyLand.