An unloading plunger having a chamber for compressed gas and a method for unloading liquid from a wellbore via ascending of the unloading plunger including ascending via formation pressure the unloading plunger from the bottom portion of the wellbore to a rest position at a wellhead and releasing compressed gas from the chamber into the wellbore during the ascending to decrease hydrostatic pressure of liquid in the wellbore above the unloading plunger.