Variable vaneless diffuser with moving floor

A variable vaneless diffuser includes a shroud, a backing plate, a divider plate adjacent to the backing plate, a floor plate adjacent to the shroud, a plurality of standoffs formed on the divider plate, and a plurality of clearance slots formed in the floor plate. The divider plate is between the shroud and the backing plate. The floor plate is between the shroud and the divider plate and is movable relative to the divider plate. The plurality of standoffs and the plurality of clearance slots define a flow path for fluid flow. The flow path has an area which is variable through movement of the floor plate relative to the divider plate.