Here is a private submarine that lets you explore the underwater world in a rich fashion. The Super Yacht Sub 3 is capable of diving to 300 meters. It has space for up to 3 people. You get an unimpeded view, comfortable seats, and an air-conditioned environment. You can even play music from a Bluetooth system or enjoy drinks under water.
The submarine has a speed of 3 knots and endurance of 12 hours. You can find out more about it here.