Potential extensions to each of the ocean observing system‟s mobile platform networks, made possible by new technologies, are examined with respect to the value of the complete observing system. The autonomous instrument networks now have the potential for the truly global scope that will come from extensions to high latitudes, into marginal seas and the deep ocean, and by high-resolution sampling in boundary currents. The autonomous networks can accommodate new sensors, including oxygen, chlorophyll-A, and particulate organic carbon, and coordination with shipboard and moored platform programs will enable studies of the impacts of climate variability and change on biogeochemistry and ecosystems. The systems required to observe ocean surface properties, surface circulation, and air-sea exchanges merit further study since improvements in these areas will come not only from new instrumentation but through better coordination between networks and better use of research and commercial vessels. The observing system infrastructure must evolve in parallel with the system‟s scope and complexity. Expanded roles are seen for smaller research vessels, including instrument deployment and recovery, reference-quality profile measurements and underway surface observations. The data management system must provide the rigorous control needed for the production of research quality datasets. The challenge in providing these enhancements to the ocean observing system is to define and achieve an optimal mix of shipboard and autonomous observations to deliver climate-quality datasets in a cost-efficient manner that exploits the synergies between satellite and in situ observations.