The only manned submersible that could reach the missing Titan is owned by Steam's Gabe Newell
https://beehaw.org/post/678902

The only manned submersible that could reach the missing Titan is owned by Steam's Gabe Newell - Beehaw
Yeah the sad part is that, really, the best we can hope for is a post mortem. Rescue is almost impossible in this situation.
Something this small could simply be floated to the surface. With big things there no way that can be done. Still difficult af but possible, don't know if things like that already exist.