In the small but exclusive world of personal submarines, there are two brands: U-Boat Worx and Triton. The two go mano a mano for the most part, offering a range of subs for different missions, ...

Triton’s Project Hercules, a concept unveiled at the Monaco Yacht Show, promises to rewrite the rules of design for mini-subs. It can dive to 656 feet, but its speed is even more noteworthy. Hercules ...

But the price tags, size and weight of the underwater craft have kept most potential buyers away from ownership. You have to be a billionaire and own a very large superyacht. Until now. U-Boat Worx’s ...