OpenROV has been blowing people away from the get-go. Check out this lovely video that details the project, part of Driven, a video series at Mens Journal.
If you’re not familiar with it (and haven’t watched the video) OpenROV is an open source submersible project created by David Lang and Eric Stackpole. It was successfully kickstarted, it was featured on the cover of MAKE Vol. 34, and it fits into a suitcase!