Differently from other underwater vehicles, underwater gliders move by buoyant changing power of their body. By this method, underwater gliders can navigate for a long time and distance. And they can move very silently by running the thrusting actuator only at the bottom of profile moving. By these characteristics, underwater gliders have been used not only at commercial area but also at military area. This paper describes the developing procedures and characteristics of a high-speed underwater glider“Marlin”. At first, the operating principles of underwater gliders are described. And next, it is mentioned how its principal components are designed. Finally, it shows the design and product results.ing actuator only at the bottom of profile moving. By these characteristics, underwater gliders have been used not only at commercial area but also at military area. This paper describes the developing procedures and characteristics of a high-speed underwater glider“Marlin”. At first, the operating principles of underwater gliders are described. And next, it is mentioned how its principal components are designed. Finally, it shows the design and product results.