Abstract: A watertight vertically elongated rigid shell or hull of a size small enough to be transportable over highways has a detachable snorkle extending from its top and contains a power source which may be used to drive pumps within the device and/or to drive mechanical devices, such as rotating blades, winches, belts, drills or propellers, which are located externally of the hull. The hull of the device is divided into upper and lower compartments, of which the lower compartment can be completely or partially flooded with water which acts as a ballast helping to stabilize the device and controlling submersion thereof and its submerged position.