Let me also be honest, and tell you that if it was me on that board, then at my age, they will have to book a hospital ward for me :)

The good news is that I found the reason for the pipe below the board, and you are right as they are called "Motor Driven Surfer Boards" An electric motor is fitted inside at the bottom of the pipe. They are also called jet boards, and electric surfboards.

Thank you for the compliments.

!PIZZA
!BEER