So I build a city on the ocean floor out of handwavium, Bioshock style, but I want an easier way to get there besides taking a boat to the middle of nowhere and then getting into a submersible.
I have an idea to dig a shaft deep into the ocean floor, and then make a tunnel leading to a near-by island, and if it goes well maybe extending to the mainland eventually.
Obviously once you go down to the ocean bottom there is a lot of pressure, but I'm thinking that by going down below the bottom the seabed will provide enough support to keep my tunnel from collapsing so I can have a dry path to run a rail line.
Is this a workable plan?
The feasibility of the city itself isn't a concern with this question. I'm just looking at a way to get to it.