Modern design approaches are conceived and utilised in an integrated loop covering system statics, dynamics, optimisation, and others. In this regard this paper presents a computing based integrated design approach for a flexible buoyancy system (FBS) aimed towards the applications in autonomous underwater vehicles and gliders. The primary design alternatives for the FBS are: piston and pump driven and both are investigated. The primary design of autonomous underwater vehicles and gliders is computed from first principle of mechanics and defined in the computer aided design model and it is implemented in the Matlab*TM. Lastly, to show the application of the present approach, a design example is presented for a water depth of 6000 m. © 2018, DESIDOC.