Abstract: A sensor based vehicle flotation device is suitable for floating a vehicle immersed in sufficient water to activate a protected water sensor and, if desired, to confirm through auxiliary sensors whether a hazardous condition is presented. When such a device detects and verifies that the vehicle is becoming immersed in water, one or more expansible chambers, affording sufficient buoyancy to allow the vehicle to float, automatically and rapidly inflate by means of compressed, pumped or pressurized gas. Upon the successful deployment of the expansible chamber, the land vehicle will begin to float, limiting water damage to the vehicle and/or bodily harm to its occupants, and reducing the risk of the vehicle overturning. The expansible chamber will remain inflated until the land vehicle is returned to safety, and the device is detached from the land vehicle.