The traditional rigid pressure devices for detecting underwater weak disturbances are limited by their non-flexible and bulky, making it difficult to deploy on small and mobile platforms. Conversely, the flexible pressure sensor with conformal capability is a kind of effective alternative strategy. In this work, a pseudocapacitive iontronic pressure sensor based on MXene electrodes and porous electrolyte foam is presented. Benefiting from the fast redox reaction in interface, the unit area capacitance has made a huge leap, which has promoted the improvement of the relative change in capacitance. Our sensor demonstrates superior sensitivity (S max >3155.4 kPa -1 ) and high-pressure resolution (150 Pa under 1.5 MPa or 0.1%). The proposed sensor has the possibility to be designed as marine electronic skin to detect the underwater disturbances.