Toba.
There were many large ferries in the surrounding waters. They were connecting to the various islands, and providing shortcuts to other parts of the mainland.
So why the interest in air and water temperatures? And the viewing area?
This! There is going to be a pearl diving demonstration, just like the good old days! This was actually a women's job back when.
I took this close-up, and while in the good old days the divers were topless and wore a short skirt, now they are fully covered. And you can see a wetsuit under that cover!
The women jumped in one at a time, each taking a half-barrel in tow. Regarding the wetsuits: they were only visible with the zoom lens.
The boat operator slowly chugged by the viewing area, and the three demonstration divers all jumped in.
And down she goes! She is wearing thin, wet, white fabric... ok, it's a good thing they were wearing wetsuits!
You can still see the white shape of the diver under water. It is not deep.
And she found one! I'm not sure that those are the hands and finger nails of someone who does heavy physical work...
And down she goes again!
And another sucess! Once the demostration was over (it was every 30 minutes, or so), they dumped the oysters back into the water, for the next demonstration!
This is a fanciful portrayal of the actual location.
This is a very fanciful portrayal of the diving! Ok, I make a poor tourist sometimes...
...next page.