Applicants have created a method and system of deep sea mining comprising mining SMS (Seatfloor Massive Sufilde) deposits from the sea floor with a subsea miner (105), pumping the solids from the subsea miner through a jumper (115) and pumping the solids from the jumper up a riser (130) to a surface vessel (195). Further, applicants have created a method of deploying a deep sea mining system, comprising stacking a riser hangoff structure (705) on top of a subsea pump module forming an assembly; picking up the assembly by a hanging mechanism, hanging the assembly on a moon pool (400), attaching a first riser joint; disconnecting the riser hangoff structure (705) from the assembly; and attaching at least one second riser joint to form the riser (130).