So Jayce and Viktor built a diving suit that increased the wearers strength (or at least had plans)

Heyyyy thats a cool link to pick up one of the lore abandoned champions good catch

They didn't build a diving suit they built "mechanized construction suit" meant to enhance the user's strength.

I noticed that, too, but Nautilus is a Bilgewater champ. I guess it's possible one of these suits was ported over to Bilgewater for an expedition. But the purpose of Naut's suit isn't to increase his strength for labor, it's just for diving to the deep depths.

However, all of Nautilus' problems are not from the suit itself, but more from the deadly horrific black goo of the deep and his asshole crew.

Pretty good theory there. Hats off to you!

Its not a lake.

Its an ocean.

Doesn't seem like that the prototype of Viktor's prefered version ever came into construction/Prototype, so I don't think so.