Abstract: The invention is to a method for the hydraulic mining of coal of varying hardness. It is described in particular as to coal of the type occurring in the Balmer Seam in British Columbia. By the method at least two parallel spaced entries are driven upward through a seam of coal. Monitors are positioned in each entry. Each monitor is horizontally and vertically pivotable, and has nozzle means from which a jet of water under a pressure of about 1900 - 2200 p.s.i. is emitted. The high pressure jet cuts the coal, which is then fed to a machine that breaks and crushes the coal into sizes wherein the resultant coal/water slurry will flow down a sloped flume into a dewatering station.The method further embodies differentially retreating along adjacent parallel entries by increments of desirably at least about 40 feet each.