In order to improve knowledge about the fluid-circulation within the Sea of Marmara, the IFREMER group have carried out pore-water extraction and thermal measurements in some selected fluid-active sites. Main focus was the Western High as gas hydrates have been recovered there, and there is ongoing study on their dynamics. A total of 7 cores have been collected on the Western High: 3 on the Northern part of the fault; 3 on the Southern part of the fault and 2 within the fault zone. Upon recovery, the pore waters have been collected for each core and for 4 selected cores, the measurement of the alkalinity has been performed on board. Thermal measurements have also been done on 5 sites (Cores 9A; 8A; 3A; 7I and 10A (Figure 1 & Table 1). Furthermore, we have extracted the pore-water from cores collected on the Izmit (ML04 & ML05) and Gemlik gulfs (ML-01_2) where no seeps activity has been characterized.