An unmanned vehicle comprising: a body; a frame structure extending from the body and supporting a plurality of propeller assemblies, each propeller assembly including at least one propeller (42, 46) and a corresponding motor (44, 48), the motor (44, 48) housed in a watertight housing or coated and made corrosion resistant; wherein each propeller assembly comprise at least one upper propeller and/or one lower propeller; the upper propeller and the lower propeller are supported for rotation by a bracket; at least one sensor (52, 54) is configured to determine when the lower propeller subset of the at least one propeller, the upper propeller subset of the at least one propeller or both are at the transition between the air medium and the water mediums medium; the sensor (52, 54) signals to a controller when the lower propellers are about to enter the water, when the lower propellers are submerged in the water or when the upper propellers are about to enter the water; the controller may stop and start the lower propellers and/or the upper propellers; the lower propeller rotates in a plane positioned below a plane in which the upper propeller rotates, wherein the plurality of propeller assemblies are configured for independent operation of the upper propeller and the lower propeller so that the upper propeller and lower propeller (i) operate simultaneously to control propulsion when the unmanned vehicle is fully immersed and being propelled in either one of both an air medium and a water medium, and (ii) operate sequentially when are configured for independent operation of one another as the unmanned vehicle transitions between the from an air medium to a and water mediums medium. a body; a frame structure extending from the body and supporting a plurality of propeller assemblies, each propeller assembly including at least one propeller (42, 46) and a corresponding motor (44, 48), the motor (44, 48) housed in a watertight housing or coated and made corrosion resistant; wherein each propeller assembly comprise at least one upper propeller and/or one lower propeller; the upper propeller and the lower propeller are supported for rotation by a bracket; at least one sensor (52, 54) is configured to determine when the lower propeller subset of the at least one propeller, the upper propeller subset of the at least one propeller or both are at the transition between the air medium and the water mediums medium; the sensor (52, 54) signals to a controller when the lower propellers are about to enter the water, when the lower propellers are submerged in the water or when the upper propellers are about to enter the water; the controller may stop and start the lower propellers and/or the upper propellers; the lower propeller rotates in a plane positioned below a plane in which the upper propeller rotates, wherein the plurality of propeller assemblies are configured for independent operation of the upper propeller and the lower propeller so that the upper propeller and lower propeller (i) operate simultaneously to control propulsion when the unmanned vehicle is fully immersed and being propelled in either one of both an air medium and a water medium, and (ii) operate sequentially when are configured for independent operation of one another as the unmanned vehicle transitions between the from an air medium to a and water mediums medium. (i) operate simultaneously to control propulsion when the unmanned vehicle is fully immersed and being propelled in either one of both an air medium and a water medium, and (ii) operate sequentially when are configured for independent operation of one another as the unmanned vehicle transitions between the from an air medium to a and water mediums medium.