Cannot claim through mountain or sea problem

[Ancient]

So I started up a new save game and have been playing for an hour or two, I chose the place where I was because there was nearby iron and coal to mine. However to my surprise I'm blocked by the "Cannot claim province through moutain or sea", I am unable to claim anything above this mountain which seems a bit stupid and broken to me?

https://i.imgur.com/0DS5Ewh.jpg

[niddhoger]

Hmmmm, it looks like you might be able to do shallow water claims. Grab the island to the NW, then the iron valley to the east of that.

It would be it's own research option.

There used to be a deep sea claim as well, but there should be a mountain one too. Especially a mountain one where you can then build a tunnel through it.