US Patent 10000264 Underwater watercraft

An underwater watercraft including a passenger compartment and an ingress egress port in which the watercraft has buoyancy and center of gravity adjusted to maintain a generally level or other desired attitude when submerged, and an angled attitude at a water surface for ingress/egress. The attitude also is adjustable via the placement of ballast and optionally including a movable ballast that adjusts the location of the center of gravity as desired. The ingress-egress port optionally includes an entry elevated from a main passenger compartment, that has an angled orientation in a submerged mode, and an optional orientation generally parallel to the water surface in a surface mode.