While the gas tanks looked odd, the size of the submarine was large enough to stave off most predators with its camouflage. The side viewport provided great views of the deep, navigation handled deftly through the front "eyes".
The funding had come through multiple Venture Capitalists. Certainly not shell companies and disguised charities. The VCs often deserved their disappointment.
The attack was soon. They believed their ancestors Nemo would be proud.