Look, you take this gigantic tub(, i.e. Starship) of flammable material, you land it safely somewhere, you attach some kinda inflatable raft around the top/side

Look, you take this gigantic tub(, i.e. Starship) of flammable material, you land it safely somewhere, you attach some kinda inflatable raft around the top/sides of it, you wire yourself up to the gas tanker on the surface, you light those rockets and let 'em rip! It'll be the steam-cleanest Starship-converted-to-ice-submarine in the system ..