Today's watch is not powered in the normal way, as it requires water to work.
The watch contains a water activated battery. The battery required water to work, and is depleted with use - the watch is not water powered (as is often mis-reported). The way it works is that the battery does not contain the electrolyte that is required in a normal battery, and so does not produce a voltage. When water is inserted through the holes in the left side of the watch, the water enters the battery compartment, wets the internals acting as the electrolyte, and power is produced. When the watch dries out, power is lost again, and the watch remains dormant until more water is added.
The watch module is quoted as PM3/W282NZ and has time, date, and seconds display modes.
These watches were initially released in the late 70s, but have been manufactured in the millions. This particular watch was a promotional model for Autotag (car accessories).
