National Workshop on Passive Acoustic Sensors, Measurements and Calibration--This workshop was held at NIOT Chennai,  on October 14, 2016. Twenty-seven individuals participated in the meeting, including representatives from the Indian Navy, fisheries agency, National Institute of Oceanography-Goa and the Indian Institute of Technology-Delhi. The workshop was opened with an inaugural presentation by Dr. S.C. Shenoi, Director, NIOT, followed by a talk on the importance of passive acoustics for monitoring underwater environments and the objectives of IQOE by Dr. Bishwajit Chakraborty, CSIR-NIO. Dr. G. Latha covered detailed technical aspects of passive acoustics and work carried at the NIOT over the past decade.  Dr. G. Ramdas spoke about underwater acoustic techniques, both including active and passive approaches. Ms. Malarkodi described the Acoustic Tank Facility and detailed the calibration work being carried out at the NIOT facility. There were lab visits and a panel discussions on passive monitoring and related technical issues by the participants.