Embodiments of the present disclosure disclose a Black box with Satellite Transmitter (BSAT) for underwater vehicles. The BSAT provides a mission data backup of sunken under water vehicles and it is akin to a black box recorder of aircrafts. The BSAT comprising a sealed enclosure to receive and transmit IR and electromagnetic signals, a Global Positioning System (GPS) with an antenna to provide GPS parameters of the BSAT, a transmit antenna to transmit the GPS parameters and parameters associated with the underwater vehicle, an ejection mechanism to eject the BSAT from the underwater vehicle on detecting a pre-defined condition, by an electronic controller. The electronic controller to perform at least one of sending control signals, communicating using IR transceiver, acquire and store underwater vehicle parameters, identifying an ejection instant, acquiring and storing data GPS parameters, scheduling data transmission through a satellite after ejection of the BSAT from the underwater vehicle.