Abstract: An object that is selectively movable through a fluid in which the object is at least partially immersed and which is adapted to automatically change between different operating states without operator intervention. A movable object has a vessel / balloon with first means having first and second states for causing the vessel to move within the fluid. The first means in the first state thereof cause the vessel to move along a first travel path. The first means in the second state thereof cause the vessel to one of a) move along a second travel path within the fluid which is different from the first travel path and b) remain substantially in a static state within the fluid. Second means are provided on the vessel for automatically changing the first means from one of its first and second states to the other of its first and second states and back to its original state without intervention by an operator.