All stations would need to be rebuilt; track ballasted; new sleepers, possibly rails, and rolling stock purchased; plus costs incurred for ongoing employment of railway staff and track maintenance crews.

Source: https://www.echo.net.au/2023/08/towards-the-future/

It weighs 20,000lb in the air, but is ballasted to be neutrally buoyant once it reaches the sea floor, the company said.

Source: https://jerseyeveningpost.com/morenews/worldnews/2023/06/19/search-under-way-as-submersible-that-takes-people-to-see-titanic-goes-missing/