The guys from OpenROV had their underwater explorer on display along with some videos of how it operates.

The project is based in Silicon Valley and a year ago ran a Kickstarter campaign which was oversubscribed with 484 backers and $111,000 of a $20,000 goal raised.

You can order parts and assemble yourself, order a fully assembled unit or download the design files and laser cut and 3d print the parts yourself. I know some yacht owners who would love one of these.