The present invention relates to a plant for storing gas under pressure. The plant includes at least one basin filled with a liquid, one or more pressure vessels located in the basin for storing the gas including interconnecting piping and connections to a gas supply and a gas discharge network, an anchoring system for supporting the vessels, a cover with a slanted surface on the underside for covering the basin which will lead any gas leak occurring in the basin towards and through a vent, and at least one gas detection equipment located in the vent. The plant is especially suitable for storing compressed gaseous hydrogen and can be connected to a hydrogen fuel replenishment system.