A pitch, roll and depth controllable towed vehicle has been developed and named as “FLYING FISH”. The towed vehicle equips with an acoustic Doppler current profiler (ADCP), CO₂ analyzer and sensors for measuring temperature, salinity, dissolved oxygen, PH, turbidity, chlorophyll. Flying Fish enables us to obtain the space continuous data of physical and chemical properties in the ocean upper mixed layer efficiently. Its maximum submerged depth is 200 m. The length is 3.84 m, breadth 2.26 m, height 1.4 m, weight in air 1400 kg and weight in water is about 0 kg. Numerical simulations were carried out in order to design mechanical parts of the control system and estimate the accuracy of motion control of Flying Fish. The simulations are based on the six degree freedom motion equations for underwater vehicle and lumped mass method for the towing cable. Field experiments were conducted to confirm the performance of Flying Fish and accuracy of numerical simulations. Results of field experiments and numerical simulations are compared.