  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 3x10^{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, finding no strong correlations.
