Abstract: An apparatus, system and method for releasing fluid from a subsea marine riser is disclosed. A housing defines an interior space and an exterior region. The housing includes first and second ends adapted for respective sealed connection in a marine riser assembly. The housing may be defined on its interior space by a central cavity adapted for passage of a drill string. A plurality of ports may be provided for fluid release from the housing upon emergency disconnect of the riser from a subsea well. One or more gates may be provided in mating configuration with the housing. The gates may be moveable from a sealed position that restricts fluid flow through the ports to an open position that facilitates fluid release from the riser through the ports.