From an APV to a superyacht, Highland Systems has a history of producing remarkable military vehicles. Even if most seem like fantasy, at least one prototype has been produced for most of them.
This brings us to the armored submarine Kronos. It is about 30 feet long, was inspired by a ray, has 11 seats (including the driver), can dive to over 800 feet, and can hold up to 11 people.
With a combined duration of up to 54 hours, it combines a diesel generator with a 1,200-hp electric jetski motor to reach speeds of up to 50 mph over the water and 30 mph below it.
It includes upward-folding wings for trailering and other amenities like adaptive lighting, an automatic life support system, and air conditioning. It weights 22,000 lbs, so make sure you have a strong transporter. The torpedo launchers are presumably exclusively for military use.