Embodiments of a buoyancy dissipater and method for deterring an errant vessel are generally described herein. In some embodiments, a volume of gas is generated from a propellant and diffused below a waterline of a vessel. The resulting gas bubble dissipates the buoyancy of the vessel providing a non-lethal deterring effect. The buoyancy dissipater includes a diffuser having radially-positioned diffusion ports to radially diffuse the gas generated by a gas generator below the waterline. In some embodiments, the radially-positioned diffusion ports comprise holes positioned radially around the diffuser to diffuse the gas around the buoyancy dissipater.