Methods and systems for underwater gas pressurization and liquefaction

An underwater natural gas liquefaction method comprising:

• pressurizing the natural gas in at least one vertical vessel by cyclically:
• introducing the natural gas into a top of the at least one vertical vessel;
• introducing a pressurizing liquid into a bottom of the at least one vertical vessel to pressurize the natural gas;
• separating the pressurizing liquid from the natural gas by a layer of water immiscible liquid which is set upon a layer of aqueous salt solution, wherein a density of the pressurizing liquid is higher than a density of aqueous salt solution, which is in turn higher than a density of the water-immiscible liquid, to maintain the layer of aqueous salt solution on top of the pressurizing liquid and to maintain the layer of water-immiscible liquid on top of the layer of aqueous salt solution;
• and
• evacuating the pressurized gas through the top upon reaching a specified pressure;
• wherein the introducing the natural gas is carried out by evacuating the pressurizing liquid from the bottom of the at least one vertical vessel.