Integrated Ocean Drilling Program (IODP) Expedition 337, originally scheduled for 15 March–21 May 2011, was postponed because of the earthquake in Japan on 11 March 2011. This addendum to the Expedition 337 Scientific Prospectus presents revised schedule and operations information for the rescheduled expedition, which will drill and study the deep coalbed biosphere off the Shimokita Peninsula in the northwestern Pacific using the D/V Chikyu. This expedition aims to extend the maximum penetration of scientific ocean drilling to over 2200 meters below seafloor and will explore the microbial ecosystem associated with a deeply buried coalbed (i.e., a habitat that had never been accessed by previous scientific ocean drilling).