It's a cool proposal. A UAE-based infra company named National Advisor Bureau has said that it plans to construct an underwater rail network between Fujairah in UAE and Mumbai in India. This will be a high-speed rail that is expected to boost the economic ties between the two countries when it becomes operational.

The aim, mainly, is to facilitate the trade of oil from the port city of Fujairah to Mumbai and of Narmada River water from the latter to the former. It will be open for passenger transit as well.

The project will be a 2,000 km long, floating network. The proposal is at a nascent stage. Big bang projects like these typically take years to see completion.

Floating trains are a known advancement in China and Japan.