Dolphin submarine
Submarine is very useful. It is capable to take us down to the underwater. While compared with real fish, especially dolphin, conventional submarine sucks. However, I bet you gotta be surprised after viewing a dolphin submarine like this.
This is the upgrade version of the dolphin submarine. It is can even act like a real dolphin, including leaping out of the water which is impossible for any other submarine or boat.
Video demonstration after the break