Fumaroles occur when groundwater is heated by geothermal sources at a shallow depth, forcing steam and volcanic gases out of the Earth's surface. Fumaroles are ubiquitous geothermal features, yet little is known about the microbial communities inhabiting these hyperextremophilic environments. From the few environmental surveys of fumaroles located on the Big Island of Hawaii, a surprisingly wide diversity of both Bacteria and Archaea has been revealed. These islands are geologically young and geographically isolated from other geothermal environments, begging the question: where did these microbes come from? I hypothesize that current microbial communities in fumaroles of the Big Island of Hawaii constitute a mixed-community due to multiple colonizations from a variety of different sources.