According to National Advisor Bureau Limited (NABL) the project is an underwater train tunnel, that is planned to connect the UAE and the other GCC countries for the first time in India. The project will consist of a subsea Tunnel and an Ultra Speed subsea railway line. The Concept of the Tunnel is based on well-known technology applied to floating bridges and offshore structures & immersed tunnels.
Specifically, the Fujairah-Mumbai Tunnel & Subsea Ultra Speed Train Line Project is currently at...
https://safety4sea.com/watch-nabl-presents-fujairah-mumbai-underwater-train-tunnel/