Aqualand Diver 200 m

In the middle of the recessed battery compartment...
You can see the five pinions of the analog gear train. Very very tiny wheels are at work here. I have a couple of times disassembled a Quartz movement gear train and found it always to be a lot harder then on mechanical watches. The toughest part is always the rotor; which is magnetic and which likes to "jump" out of place disarranging the whole train.
Why are the pinions of the gear train exposed and accessible here? Probably to apply a bit of oil during a battery change.