Abstract: A hydraulic underground mining system for operating through a small diameter borehole into a subterranean body. An elongated mining tool includes a liquid jet nozzle that is movable in a vertical direction along the length of the mining tool for forming a directed jet stream to impact material in the ore body and convert the material into a slurry. An orifice is positioned below the jet so that slurry flows into the orifice, the latter being connected to a jet pump which returns generated slurry to the surface. Suitable hydraulic power means are provided for operating the jet pump and for moving the jet stream in vertical and circular directions. Means for monitoring and controlling the progress of mining and the condition of components of the system are provided to monitor and control the system from a centralized location.