A deep–towed multi–sensor sonar sytem that comprises a two–sided 30 kHz sidescan sonar, a 7.5 kHz sub–bottom profiler sonar, a magnetometer, a temperature probe, a transmissometer, and a range of vehicle handling instruments. TOBI is towed on a 200 meter umbilical behind a 600 kg depressor weight attached to the surface ship via the main 0.68 in. armored coaxial cable, which reduces ship–induced heaving that influences the stability of the vehicle. The sidescan sonar has a range of 6 km and a seabed footprint ranging from 4 by 7 meters close to the vehicle to 42 x 2 meters at longer ranges, and the profiler sonar can penetrate up to 60 meters into soft sediments with a vertical resolution of better than 1 meter. This instrument was developed by the IOSDL.