The methods and software interfaces used by ocean observatory operators and scientist users to access data generated by sensors and instruments attached to research observatories vary widely from facility to facility. The tools used to access instrument metadata and to control various instrument functions are also variable between observatories. An effort has begun in the US to define software standards that could be implemented at any ocean observatory to provide access to oceanographic instruments independent of the observatory on which they operate. Interoperability also enables the seamless combination of data streams from more than one observatory into a virtual ocean observatory. This paper describes the concepts and a proposed process to develop interoperability standards for ocean observatories.