The proposal "Underwater passive acoustic monitoring of cetaceans using underwater gliders – ΥΠΑΚOUE” was submitted in the frames of the free access to the nodes of the research infrastructure of the "Hellenic Integrated Marine Inland water Observing, Forecasting and Offshore Technology System - HIMIOFoTS". The proposed project, which was successfully evaluated, concerns the integration of an autonomous acoustic recorder in an underwater glider of the HIMIOFoTS infrastructure for monitoring cetaceans and environmental noise in the Cretan Sea. The glider is conducting usually four missions a year, monitoring the seasonal variations of physical and biochemical parameters of the sea water up to 1000 m depth. During its next mission (March 2020), the glider will also record passive acoustic data for detection of different species of cetaceans with different depth preferences up to 1000 m. The proposal was submitted by Dr. Kalliopi Gkikopoulou (team: Mark Johnson, Rene Swift, Douglas Gillespie) of the Sea Mammal Research Unit, Scottish Ocean Institute, University of St Andrews. The autonomous acoustic sensor (hydrophone) was attached on the glider by the HCMR dedicated team and then the glider was prepared for its next mission (week 17 – 21/02/2020). On the 25/02/2020 sea trials were also performed in the Saronic Gulf, in order the glider to be thoroughly tested for its stability, efficient surfacing position and satellite communication, while the autonomous sensor is attached on main body of the underwater vehicle. The glider will be deployed in the Cretan Sea for its next mission during the week 9 to 13/03/2020, which will last approximately 40 days.