A team of marine researchers is developing a blueprint for an inexpensive tool to collect oceanographic data, a venture they hope will make ocean science more accessible to other scientists, educators, and marine enthusiasts. Using an open-access model, the researchers hope to build their own CTD, a widely used oceanographic instrument that collects information on ocean temperature, depth, salinity, and density. While CTDs are vital to marine research, the technology can be prohibitively expensive for some “citizen scientists,” with costs running $5,000 to $25,000 per instrument. Traditional CTDs are small, cylindrical instruments that are dropped from boats and relay data back to shipboard computers. Using a crowdsourcing website, organizers of the so-called OpenCTD project are raising funds to design a CTD capable of collecting ocean data down to 200 meters at a cost of about $200.