https://www.thenextmiami.com/elon-musk-says-he-wants-to-build-tunnels-under-miami-to-solve-traffic/

https://qz.com/1051061/elon-musks-boring-company-is-actually-boring-and-thats-what-will-make-it-such-a-huge-success/

I think people who say they can do anything are bound to make serious mistakes only for others to pay for it.  The Boring Company is a new kind in the block without much tunneling experience.

Boring tunnels in a city barely over the water level, like Miami, is different from doing it in the Las Vegas desert.

"Building a tunnel under a city like Miami would involve waterproofing the structure during construction to ensure that construction equipment doesn't get damaged and then maintaining a waterproof seal to avoid leaks while people drive through the tunnel."

https://www.miaminewtimes.com/news/elon-musk-proposes-digging-tunnel-in-miami-11810719

Elon Musk tells Miami Mayor Suarez he’s interested in a tunnel for electric vehicles under Brickell Avenue Bridge for $30m

https://www.miamiherald.com/news/local/community/miami-dade/article249037895.html