Another large highway project is scheduled to be inaugurated in Mumbai. A 9 kilometer section of the 'Coastal Road' (also known as the Western Freeway) will be inaugurated on February 19, from the Bandra-Worli Sea Link in the north to Marine Drive in the south.
Most of the project is a structure along the coast, but it also includes a tunnel under a hill and under a beach, making it a de-facto undersea tunnel (though only marginally offshore).
The only decent size photos I could find seem to be from a while ago.
(https://i.imgur.com/ADK5O0p.jpeg)
(https://i.imgur.com/hw5gqbP.jpeg)
(https://i.imgur.com/hlV1zis.jpeg)
First section of this should open in May. It will be an incredibly impressive road. It will surely have traffic jams but will be worth it to increase mobility.
https://www.worldhighways.com/wh8/news/indias-us17-billion-mumbai-coastal-highway
Another 3.5 km stretch of this road will open on Monday:
https://www.msn.com/en-us/travel/news/3-5-km-stretch-of-mumbai-coastal-road-to-open-for-vehicles-from-thursday/ar-BB1pKUE0?ocid=BingNewsSearch&cvid=c4d7c15babd94d5a9edb01900bc60502&ei=45
This stretch was already open to traffic southbound, but not northbound. It has opened to traffic today, but will initially only be in operation from Monday to Friday between 7 am and 11 pm, to complete construction.
https://www.financialexpress.com/business/roadways-mumbai-coastal-road-project-3-5-km-north-bound-stretch-opens-for-vehicles-heres-when-it-will-be-accessible-3550267/
This satellite image from March 4, 2024 shows the half completed expressway, a few days before it opened for southbound traffic on March 11. It is now also open northbound.
(https://i.ibb.co/mcFz8fJ/Mumbai.jpg)