What's interesting to me is how many times James Cameron has been to the Titanic, I believe 33 times. Plus he's taken his one-man sub to the bottom of the Mariana Trench. He pilots a single seater and it looked infinitely safer than that sewer pipe "tourist" sub. Still not without risk, but Cameron has mitigated as much risk as possible.
James Cameron to Mariana Trench. That's 7 miles down, not 2 1/2.
https://www.npr.org/sections/thetwo-way/2013/05/23/186302916/Mariana-Trench