A mechanical seal configured for sealing a pressurized, compressible fluid within a sealed volume, the seal comprising: a rotating sealing ring surrounding a rotating shaft, the rotating sealing ring being rotationally cooperative with and sealed to the rotating shaft; a stationary sealing ring cooperative with and sealed to a housing that is penetrated by the rotating shaft, a stationary seal face of the stationary sealing ring being substantially parallel to a rotating seal face of the rotating sealing ring, the rotating and stationary seal faces (112, 114) being separated by a seal gap such that the compressible fluid can only escape from the sealed volume by passing through the seal gap; characterized in that said seal further comprises: at least one shock inducing section (116, 118, 120) included in the seal gap, the shock-inducing section (116, 118, 120) including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment; the converging and diverging segments (200, 202) being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section (116, 118, 120) into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment, thereby reducing a stagnation pressure of the fluid. a rotating sealing ring surrounding a rotating shaft, the rotating sealing ring being rotationally cooperative with and sealed to the rotating shaft; a stationary sealing ring cooperative with and sealed to a housing that is penetrated by the rotating shaft, a stationary seal face of the stationary sealing ring being substantially parallel to a rotating seal face of the rotating sealing ring, the rotating and stationary seal faces (112, 114) being separated by a seal gap such that the compressible fluid can only escape from the sealed volume by passing through the seal gap; characterized in that said seal further comprises: at least one shock inducing section (116, 118, 120) included in the seal gap, the shock-inducing section (116, 118, 120) including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment; the converging and diverging segments (200, 202) being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section (116, 118, 120) into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment, thereby reducing a stagnation pressure of the fluid. at least one shock inducing section (116, 118, 120) included in the seal gap, the shock-inducing section (116, 118, 120) including a converging segment within which a cross section of the seal gap narrows followed by a diverging segment within which the seal gap widens, so that a local minimum in seal gap width, referred to herein as a "choke point," is formed between the converging segment and the diverging segment; the converging and diverging segments (200, 202) being configured to cause the compressible fluid when flowing radially or axially outward through the seal gap to be accelerated within the shock-inducing section (116, 118, 120) into a supersonic state, so that a shockwave is formed by the fluid within the diverging segment, thereby reducing a stagnation pressure of the fluid.