Billed by its Florida-based manufacturer as the world’s deepest-diving submersible with a transparent acrylic hull, the Triton Submarines Triton 6600/2 (tritonsubs.com) is designed to take its pilot and passenger 6,600 feet below the surface of the ocean. The passenger compartment remains at surface pressure regardless of the depth of the dive.

The orb-shaped hull enclosing the compartment provides an unobstructed view of the surroundings, and six standard-equipment 20,000-lumen lights illuminate the view. …