Near the end of the the Thurston Lava Tube, Kilauea, Hawaii, United States
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/20818286@N00">Bryan Chan</a> from San Francisco, USA
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/bryanchan/5366277603/">DSC_1450</a>