SNAP-21 is a two-phase project to develop a series of compact strontium-90 power systems for deep-sea and ocean-bottom uses (20,000-foot depths). The first phase of design and component development on a basic 10-watt system already has been completed, and a second phase development and test effort now under way will extend through 1970. A series of power sources in the 10- and 20-watt range will be available for general purpose deep-ocean application. The SNAP-23 project involves the development of a series of economically attractive strontium-90 power systems for remote terrestrial uses. This project will result in 25-watt, 60-watt, and 100-watt units capable of long-term operation in surface buoys, offshore oil platforms, weather stations, and microwave repeater stations. In addition to the above, effort is underway by the AEC to develop an isotope-fueled heater that will be used by aquanauts in the Navy’s Sealab Program (see page 12). Future activities, now being planned, will involve the development of large isotope power sources (1-10 electric kilowatts) and small nuclear reactors (50-100 kilowatts) for use in manned and unmanned deep-ocean platforms. Ocean Engineering Considerable engineering experience has been derived from the work of federal agencies in development of the largest taut-moored instrumented buoy system ever deployed in the deep ocean. Developed by Ocean Science 81 Engineering, Inc., it is useful in observation and prediction of environmental changes. The system embodies substantial advances in design. It incorporates, among other features, an acoustically commanded underwater winch for adjustment of the mooring depth after the buoy is deployed, and for recovering a 16,000-pound submerged data-recording instrument canister. This buoy system can survive being moored in up to 18,000-foot depths of the open ocean for upward of 30 days. The very first deep-ocean, taut-moored buoy system was developed for the government in 1954, and has since become an important tool for oceanographers and others who seek stable instrument platforms at sea. The buoys have the advantage of minimizing horizontal movement due to currents, winds, and waves. The National Marine Consultants Division of Interstate Electronics Corporation has developed for the government a system for measuring the propagation of seismic sea waves (tsunamis). Work of these sorts contributes materially to reliable ocean engineering. And the measurements made by these sophisticated instruments contribute to our knowledge of ocean fluid dynamics and wave mechanics.