One of the POSEIDON SeaExplorer gliders was recovered successfully from the Cretan Sea at the end of July 2019, having completed another scientific mission. The SeaExplorer glider has been continuously sampling the water column up to 1000 m depth in a saw tooth pattern for approximately 30 days, collecting oceanographic data of temperature, salinity and dissolved oxygen. HCMR has established an “endurance line” in the Cretan Sea by accomplishing repeated glider missions throughout the year, in order to monitor seasonal variations of physical and biochemical parameters of the water. These missions have an average duration of one month, while the glider is set to sample every time the water column on the same, specific geographical path.