[v7n]

This is barely on topic, but "there aren't many submersible vessels in the world able to go so low" caught my eye and I will use this opportunity to throw shade on the US DoD as partially responsible for the lack of such vehicles in current day. Yes, I'm pretty salty about this one.

The small submersibles used for Titanic the movie for filming the wreckage were Mirs* and a marvel of engineering for their time. However "[t]he level of technology flowing into the Soviet Union raised concern in the US and Rauma-Repola [the Finnish manufacturer] was privately threatened with economic sanctions."

* https://en.wikipedia.org/wiki/Mir_(submersible)