Air gun with a volume of 30 liter, used to produce sound waves for marine refraction seismics. Maintenance during an expedition of the German polar research vessel <i>POLARSTERN</i> to the South Atlantic
<a href="//commons.wikimedia.org/wiki/User:Hgrobe" title="User:Hgrobe">Hannes Grobe</a> 23:25, 16 December 2006 (UTC), Alfred Wegener Institute for Polar and Marine Research, Bremerhaven
CC BY-SA 2.5
<span class="int-own-work" lang="en">Own work</span>