OpenROV at Sydney Maker Faire 2014
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.