Maybe the seas have just lost the hold they once had over the
imagination.

It's more likely, in a society which has lost its ability to discern a well-constructed story from a fictive, hackneyed work, that imagination has lost the hold it once had over people.

Sea-going fare is a bit more expensive to film than the average space-epic these days. While it's true that space-travelling entertainment has largely borrowed the language and story structure that once appeared only in tales of the sea, there are still watery epics being produced and audiences to go see them. The problem is that they cost too much to do realistically.

"Master and Commander," "A Perfect Storm," "Poseidon," "Cast Away," "Finding Nemo," "Blue Crush," "Atlantis: The Lost Empire," "Into the Blue," "Voyage of the Dawn Treader," Whatever that thing was with the super-intelligent sharks...

Hollywood is still trying to make ocean-going films. Unfortunately, expensive failures like "Waterworld" and "Cutthroat Island" don't help matters when a gee-whiz, space-action flick or fantasy film can be shot on a soundstage in two weeks against a green screen, and become a effects-extravaganza after a mere six months in CGI post-production.

You could film a sea epic the same way and throw buckets of water on the cast at script-appropriate moments, but the look just isn't going to be there... Filming at sea is more problematic, to say nothing of the insurance costs these days.

Settings are not as crucial to gripping the audience's imagination as storytelling is. Find the right story and the audience will enjoy it whether it is set in space, at sea, or down the street at their local Dairy Queen.

JB's Namor was my favourite rendition of the character since the'60s, and since the time JB did it. Byrne got away from the super-hero stuff and treated Namor as a character in an sf novel.

I always felt JB was influenced somewhat by the "biographical" material of Tarzan, Doc Savage, and others written by Philip Jose Farmer. Not in the sense of copying anything, but just in the general approach: What the Atlanteans' language might be like, and so forth.

Hey, maybe Namor tangled with Bruce Wayne at some time(thanks perhaps to the Marrs twins' machinations) when he was a conglomerate CEO... Oops, wrong thread.