At a fixed depth, so probably more like this: https://secure.wikimedia.org/wikipedia/en/wiki/Submerged_floating_tunnel https://secure.wikimedia.org/wikipedia/en

At a fixed depth, so probably more like this: https://secure.wikimedia.org/wikipedia/en/wiki/Submerged_floating_tunnel https://secure.wikimedia.org/wikipedia/en/wiki/Submerged_flo...