A multi-modal vehicle includes a main fuselage body; one or more wings extending from the main fuselage body and having a shape configured to provide aerodynamic lift when the vehicle travels through the air and hydrodynamic lift when the vehicle travels through the water; and a buoyancy control engine situated within the vehicle and configured to control the buoyancy of the vehicle relative to surrounding water when the vehicle is submerged in water, thereby providing a buoyancy force to selectively propel the vehicle upwards and downwards, respectively, through the water.