How do teleporters work in Steamworld Dig?

It's been a while since I played Steamworld Dig and I just picked it up again so I can finish it before starting the sequel. It looks like there are "natural" teleporters underground and also some purchasable ones that you can place anywhere along your route. And they all go to the same place above ground!

How does this work? Will it always deliver me to the most recent one I traveled back through? Or the deepest one? Or something else entirely? It doesn't appear that I can pick one to travel to.