Abstract: A method is provided for mining deep tar sand deposits which minimizes energy losses and surface subsidance due to cavity collapse. A well is sunk through the overburden and tar sands deposit into the bedrock below the deposit; the well is sealed and pressurized with steam and inert gas. Hot aqueous fluid is directed against the deposit to melt the tar and form a tar-sand-water slurry which is passed to a surface recovery plant. Pressure is maintained in the well sufficiently high to hold the overburden. Energy losses are minimized by maintaining the pressure both in the well and the surface plant above the boiling point of the water at the temperature used, which may be as high as 450.degree. F. or more, subsidence is prevented by keeping at least a 10 foot thick ceiling of tar sands throughout the operation, and by backfilling the well with an aqueous slurry of sand after mining operations are complete, before releasing pressure on the well.