Although it is implicitly acknowledged that many aspects of contemporary geothermal energy utilization are shrouded in ignorance, this is rarely appreciated or in any way well communicated. Using Jules Verne’s science fiction novel A Journey to the Center of the Earth as a means to highlight the inevitable normality of knowledge gaps and uncertainty, certain aspects are discussed that can be applied to communication strategies regarding the unknown in current geothermal energy utilization. This may be important given that risk assessments can often not be communicated meaningfully to citizens and decision makers.