Abstract: Apparatus and methods for purging water from a submerged pipeline including means for handling pipeline "pigs" (i.e., sphere, plug, or other device movable through a pipeline interior in sliding peripheral engagement therewith). In the system of the invention a pig launcher is attached at a first pipeline means end and a pig receiver is attached at a second, submerged pipeline means end. The pig launcher is operable to propel a plurality of pig elements in sequence through the pipeline under the urging of pressurized gas in order to displace fluid and/or locate obstructions. The pig receiver is arranged to exhaust such displaced fluid and receive and store the propelled pig elements. The pig receiver may include a fluid discharge system for exhausting propulsion gas into the ambient water in response to the arrival of a pig element and thus provide means to signal such arrival.