Salinity is a critical environmental parameter governing ocean circulation, biogeochemical processes, and ecosystem health, yet existing conductivity-based sensors remain costly and sensitive to variations in ionic composition. Here, we present a low-cost, scalable potentiometric chloride (Cl^–)-sensing platform for salinity monitoring in dynamic marine environments. The system integrates a chemically welded ion-selective membrane (ISM) fabricated via capillary-bridge printing using controlled meniscus deposition and a miniaturized Ag/AgCl reference electrode. This printing process is modeled as a function of contact angle, tip speed, and viscosity, enabling precise control of membrane thickness and interfacial bonding. The meniscus-driven deposition is coupled with polymer–substrate interpenetration, ensuring strong adhesion and structural uniformity. The resulting ISM suppresses the formation of an interfacial water layer and exhibits enhanced resistance to delamination under prolonged aqueous exposure. The Cl^–-selective electrodes exhibit a stable response at environmentally relevant concentrations, with low variability and reduced drift, while the custom reference electrode achieves stable performance with minimal concentration dependence. Ocean deployment demonstrates robust performance under strong salinity gradients and tidal dynamics. Differences between Cl^–-derived and conductivity-derived salinity measurements are analyzed in relation to ionic composition, demonstrating the complementary roles of selective and non-selective sensing.

An approach to scalable surface-drifting buoys is needed to enable the high spatial and temporal resolution of oceanographic data that the science and meteorological communities are asking for. With the number of active buoys predicted to increase by a factor of 100 or more, the impact on the environment becomes even more important. Here, we present a pathway to a scalable and sustainable generation of buoys. We identify the main criteria to be used when developing such buoys to be low cost, with reliable data and neutral or even positive environmental impact. For each buoy subsystem — hull, electronics, energy generation and storage, sensors, and communication system — cutting-edge technological solutions are presented, many of them from emerging research in marine or other disciplines. We then assess the potential solutions against the design criteria and plot a path toward small, environmentally friendly, low-cost, and low-power buoys.

Workshop participants divided into focus groups to consider resident autonomous undersea vehicle (R-AUV) use cases related to these four application areas: mid-ocean ridges and the overlying water column; gas hydrates and coastal oceans; polar, under-ice, and off-planet oceans; and maintenance and operation of installations.

The following technical elements emerged as clear common themes across R-AUV deployment scenarios: power and data management sub-systems, communications, navigation, capable sensor and payload systems, advanced autonomy functions. The single most important conclusion of the workshop is that incremental technological steps toward realizing routine R-AUV operations could yield revolutionary scientific and operational value.