The prototype ULTRAMOOR design is a subsurface mooring that supports 10 (or more) discrete acoustic current meters. Travel time and acoustic Doppler sensors are being evaluated. Each current sensor is equipped with a small, low power acoustic transmitter that transfers compressed data from its instrument to a receiver located below the euphotic zone (nominally at 500-m depth). The acoustic receiver forwards these data to an array of up to 10 expendable data capsules. In a typical scenario a capsule would release every 6 months over a 5-year deployment interval. Each capsule contains 4 Mbytes of solid-state memory and an Argos transmitter, which transfers the data via satellite as the capsule drifts away from the mooring. The initial long-term test of the ULTRAMOOR prototype was begun on November 20, 2001 offshore Bermuda. Retrieval of the system is scheduled for November 2004.