Provided is a method, system, and sensor device for identifying and detecting presence of a leak in a fluid conduit. The sensor device freely flows with a fluid within the fluid conduit. The sensor device includes an outer capsule that is free flowing within the fluid and provides fluid-tight containment to an interior compartment, at least one acoustic sensor mounted within the interior compartment, wherein the at least one acoustic sensor senses acoustic properties of the fluid to detect the presence of the leak, and a conductor for activating the at least one acoustic sensor to sense the acoustic properties of the fluid and the fluid conduit, wherein the conductor passes from the interior compartment and through to the outer capsule.