21 year old student Archie O'Brien from the UK has developed CUDA - a 3D printed jetpack. The CUDA allows you to experience speed under water thanks to the backpack that is driven by jet propulsion.
The use of 3D printing and CNC technology allowed for faster development time as well as reduced cost. Molten deposition and stereolithography technologies for used for the development of the propellant. To prevent water leakage, a layer of resin was added along with silicon seals to the backpack.
The CUDA is expected to be launched in early 2019. Not only is this something that could be fun, but also one which will be useful for use in maritime rescue and coastal emergencies!
Here's a video from the first prototype test:
Source: 3D Natives