Using Tamiya's 1/350 scale ship Serge of SP Maquettes* did the Bismarck wreck diorama.

Bismarck wreck 1
Bismarck wreck 2

His other "Sous La Mer" (that's 'Under The Sea' in French) works are amazing too. Check out his Stuka and Titanic wreck diorama.

* The site is in French

Amazing detailing on what are essentially wrecks. Obviously an immense amount of research was done. Too bad we can't click for a blow-up of the photos. Sure would have love to see how he manage the bubbles from the divers.

Thanks Harman for highlighting this one. Looks like this will be good inspiration for you and your brother to start on your dream project of Bismarck.

Hmmm... the diver's bubble appears to be added on by software. I assume Serge uses Paintbrush "Airbrush" function to add on the bubbles.

You can see the example by clicking on the thumbnails on this page.

To create the bubbles, I think we can use those clear beads (like the one in silicone packs) glued together. But at 1/35th scale, I think the bubble would be too big.

I have also seen another Bismarck wreck diorama at modelwarships.com. Basically it's a two-layered diorama - a normal Bismarck on the sea surface and the wreck underneath it.