AbstractThis paper focuses on feedback stabilization of a neutrally buoyant and bottom‐heavy airship actuated by only five independent controls (with the rolling motion underactuated). The airship is modelled as an eudipleural submerged rigid body whose dynamics is formulated as a Hamiltonian system with respect to a Lie–Poisson structure. By exploiting the geometrical structure and using the so‐called interconnection and damping assignment (IDA) passivity‐based methodology for port‐controlled Hamiltonian systems, state feedback control laws asymptotically stabilizing two typical motions are designed via La Salle invariance principle and Chetaev instability theorem. Simulation results verify the control laws. Copyright © 2007 John Wiley & Sons, Ltd.