I've seen Roman Reigns suggested before, also. But I haven't actually seen him in anything but pictures. I'll keep an eye out for him in Hobbs and Shaw, which I intend to see. It's funny, all three, the Rock, and Roman Reigns, and Jason Statham --- oops, I think Vin Diesel too, have either mentioned Namor as a possibility or have been rumored for the role. Statham actually took a meeting about the role when Universal was doing the movie. And of the four, he's actually the one who probably can handle the underwater scenes, as he was a competitive diver.
https://www.slashfilm.com/jason-stat...e-sub-mariner/
I think looks can be dealt with if the actor can act and has the presence.