A deep ocean gas storage system for storing compressed gas, the system comprising an inflexible thin walled storage vessel anchored to the sea floor having an axis located in water substantially perpendicular to and on a sea floor below sea level, a gas intake for admitting and discharging compressed natural gas to and from the vessel; a water port for admitting and discharging water to the vessel using hydrostatic pressure to discharge compressed gas from the vessel at a substantially constant discharge pressure as the volume of the gas in the storage vessel decreases when water content of the vessel increases; a conduit fluidly connected with the water port oriented substantially parallel to the axis having a discharge opening above the level of sea water in the vessel; and a valve disposed at the gas intake to the vessel for controlling compressed gas admission and discharge.