WWII Diving Bell - Concept

So I was looking at a lot of WWII mech designs and got inspired by making a more retro-high-tech version of a diving bell - here as one used by the American Navy during World War 2, to salvage sunken equipment or to look for survivors of sunken ships. 
The design itself is based on the ball turrets under B-17 & B-24 aircrafts, with a little mix of the American M4 Sherman tank. 
Originally, I was thinking of making the color scheme green, until I realized there are no green colors in the ocean, if we're talking about camouflage. 
And, for the sake of it, I named it "Nautilus", as many other underwater vessels have been named through time.