We present new high resolution neutral hydrogen ( H i ) images of the Galactic supershell GSH 242-03+37 .
These data were obtained with the Parkes Radiotelescope as part of the Galactic All-Sky Survey ( GASS ) .
GSH 242-03+37 is one of the largest and most energetic H i supershells in the Galaxy with a radius of 565 \pm 65 pc and an expansion energy of 3 \times 10 ^ { 53 } ergs .
Our images reveal a complicated shell with multiple chimney structures on both sides of the Galactic plane .
These chimneys appear capped by narrow filaments about 1.6 kpc above and below the Galactic mid-plane , confirming structures predicted in simulations of expanding supershells .
The structure of GSH 242-03+37 is extremely similar to the only other Galactic supershell known to have blown out of both sides of the plane , GSH 277+00+36 .
We compare the GASS H i data with X-ray and H- \alpha images , finding no strong correlations .