In Mio in the town of Mihama in Wakayama there's some locations that's shown in Air, so I went and checked it out.
The closest train station is Gobō Station, but the Air locations are quite far from there, so I took a taxi which cost a bit under 2000 yen.
Image from Episode 5 - 14m38s
When I arrived at the location I saw this big seawall.
Image from Episode 5 - 14m44s
From here I got a picture of this road where Haruko and Yukito is walking on in the anime.
Image from Episode 5 - 19m45s
Later in the same episode they're also seen at this small bridge nearby.
Image from Episode 4 - 08m15s
And there's also this opening in the seawall that's similar to one shown in the show. I've marked a path from Gobō Station to this place in the map below.
Image from Episode 11 - 02m55s
The rest of the location around the seawall doesn't match though.
Image from Episode 3 - 15m20s
Here's the same comparison of Misuzu walking on the seawall which I also got a picture of in Kami Town.
There was a bunch of fishing boats here, just like in Kami as well.
I luckily managed to catch the infrequent bus back towards the central parts of Mihama and Gobō, so I didn't have to walk.
This location was visited on 2016/10/20.
Special thanks to the ones who went here before: