ONC routinely schedules expeditions on major oceanographic vessels to maintain and service our cabled ocean observatories. During these exciting voyages, our engineering and technical staff use remotely operated vehicles to recover, install and connect instrument systems to our deep-sea networks . Scientific samples are also collected for sensor calibration and site characterization. Depending on the ship schedules, we strive to service each observatory site at least once per year, over three or four separate expeditions between March and October.