Data document related to the processed heat flow data acquired using the Multi-penetration Heat Flow Probe (MHFP) device at the Cascadia subduction zone during Atlantis cruise AT26-04. The document describes the heat flow probe instrumentation, methodology, and data. The data file is in PDF format and was generated as part of the project called Thermal Structure of the Cascadia Subduction Zone, Grays Canyon Discovery Corridor, Washington. Funding was provided by NSF grant OCE12-49552 (investigator Robert Harris).