The seafloor nodes for NEPTUNE must be designed to facilitate the installation or removal of a large, diverse set of instrumentation. This requires the use of wetmateable connector technology which is compatible with remotely operated vehicle (ROV) manipulators. Underwatermateable electrical connectors for this purpose are readily available and have a good long-term reliability track record. By contrast, underwater-mate- able optical connectors are an emerging technology, and are less attractive from both a cost and a reliability perspective.