My Concept is a Hybrid Sailboat/Submersible that uses a combination of traditional sail technology, combined with the biologically inspired swimming of large animals such as whales and fish. Whether it's a speedboat or a cargo ship, almost all marine transportation uses propellers as the main means of propulsion. While they are remarkable efficient, they unfortunately produce a lot of micro bubbles which form in their wake, which create a lot of sonic noise underwater which can have profound effects on animals like whales or dolphins who are sensitive to this type of noise disruption.
Companies like Festo create mechanical systems which are biologically inspired to push the technological envelope of conventional flying, walking, and swimming robotics and automation systems. For example Festo's smart bird prototype did not use a propeller, but rather the flapping motion of the wings to achieve flight. Having the the entire wing and lifting area essentially becoming one big propeller increased the efficiency of the system dramatically compared to a conventional propeller driven craft. So applying the same design process to a larger system could not only help the oceanic sonic environment( in creating a ship that creates no capitation bubbles), but the bionic propulsion method could be a much more fuel efficient way to move about the water than conventional propellers.
The Submersible aspect of the vehicle gives the passengers an opportunity to view the undersea life, while the solar sails drop down to allow for maximum maneuverability underwater.
While the mechanical technology for a concept like this might seem a little far off both in cost and maneuverability, its always nice to take some inspiration from nature and see how time has refined and shaped some of the most efficient aquatic animals.