Want a River Drifter at 400 KHz? There will be one here soon! The first River Drifters were fitted with Nortek Aquadopps with 1 and 2 MHz sensor heads and a four downward looking sensor for precision depth to bottom measurements. These drifting instruments are ideal for making detailed three dimensional profiles of shallow, active littoral environments. These River Drifters have working depths of 10 to 15 meters. Adding a River drifter with a 400 KHz Nortek Aquadopp will extend the profiling depth to 100 m. This new model will still offer the same advantages of autonomous surveying with sample records by Iridium SBD messaging and the ability to record 1 Hz Aquadopp data and GPS location data on internal storage.