Limiting Factor, now operated by Gabe Newell, having purchased it from builder, Victor Vescovo. First submersible to reach the five deepest points in Earth's oceans in 2018. 2-person vehicle. My favorite design of the lot, IMO its a thing of pure function and beauty.
Expedition Deep Ocean (TV Show) Series documenting Limiting Factor's exploration of the deep.

Deepsea Challenger, the James Cameron project to reach Challenger Deep in 2012. Single occupant vessel.
Deepsea Challenge (2014) Documentary Documentary of James Cameron's expedition.

Striver, 3-person bathyscaphe vessel designed and built in China. Reached the Challenger Deep in 2020.
I don't find a documentary of Striver, if anyone has a link, please let me know and I will post.

Trieste (bathyscaphe) In 1960, it became the first crewed vessel to reach the bottom of Challenger Deep in the Mariana Trench, the deepest point in Earth's seabed. Fascinating project, especially for its time.
Trieste documentary

The common thread connecting all of these vessels, is a maniacal focus on safety. To my understanding there has been zero serious safety accidents linked to any of these projects. That's saying quite a bit, considering the extreme environment they operated under.

If you find a mistake, or want me to add a link, just holler. Help Desk hours are from 2-230 each morning, Miercoles.