Details on the proposal here.
Never exactly been confident on the work ability of Sutton's design however it's certainly unique.
The two swimmer delivery vehicles depicted are the Proteus SDV and the Shallow Water Combat Submersible (SWCS). Sutton also shows his sub depicted with a Dry Combat Submersible however I never got around to drawing it and I'm also not as confident as him in the ability for one to fit within the Dry Deck Shelters, even if they are larger than existing ones.