Aquariums, like zoos and butterfly farms/ zoos, are a snapshot of the wild environment. When all flora and fauna are considered, they have less than 1% of the native environment. In large aquaria for example, the corals are usually fake, there are no small octopi or crustaceans, no breeding fish- just a bunch of relatively big fish, and only a few species at that.
Not to say these large aquaria aren’t marvels, or wonderful for watching the fishes; it’s just not what a diver sees. They do afford an opportunity for photography, sometimes good photos, which is nice considering that underwater photography is a lot harder than it looks!
That said, these fishes are all captive; they often aren’t from the immediate area either. Personally, I wouldn’t post them as observations.
If what appeals is the idea of being able to get a glimpse at the underwater world without having to learn to dive/snorkel, maybe it would more sense to look for options that are specifically meant for underwater viewing rather than an exclusive dining experience.
One thing that comes to mind here is fish viewing stations – i.e. near-shore structures with windows set below the level of the water. They seem to be reasonably common in North America but I don’t know if the same is true in Europe.
Another possibility would be an underwater boat tour, e.g. in a semisubmersible or glass-bottom boat.
The restaurant Under in Norway seems to be literally in the sea and is also used as a marine research station, so presumably any marine life seen there would be genuinely wild.
Many other such restaurants do seem to be part of an aquarium. Or have hair-raising prices which I doubt would justify a visit by someone who is mainly interested in the chance to see sea life.
My experience from snorkelling is that in most places in Ontario, where we only have freshwater rivers and lakes, it’s a great day if I can find 5 species of fish. On the other hand in coral reefs off the coast of Kenya I could see 20-50 species pretty quickly. Other diversity is proportional as well; invertebrates, seaweeds, sponges, corals, epiphytic organisms growing on all those things etc.
I’d assume that a marine restaurant in Norway would have significantly more diversity than inland freshwater, and tropical marine areas like the Maldives would have even more. It would depend on the precise location of the restaurant as well though.
Taking underwater photos through glass (e.g. at aquariums) can be pretty challenging because of distortion and reflections, but with some patience you could definitely get decent photos.
I’ve come across a coupleobservations of ducks underwater taken through glass walls, there are likely more examples on iNat somewhere.
No idea why you aren’t finding results. The terminology isn’t consistent but google is usually fairly good at finding synonyms.
What I was thinking of was something like this: https://en.m.wikipedia.org/wiki/File:Fish_Viewing_Window,_Bonneville_Dam.jpg
However, I didn’t have any specific sites in mind. The city where I grew up had one in the local creek, though there usually wasn’t much to see. Places where there are migrating salmon/fish ladders are likely to have such structures. Salmon migration (and the interactions with dams and water management) is a big story in the environmental history of the American West, so there is a certain amount of tourism interest connected with it.
I want to take away your fear of snorkelling. I started it two years ago, when I bought the Olympus TG6 (which was intended for insect macros). I just went to the most populated “family beach” of Málaga. There were little stone walls into the water to break the waves and retain the sand and on and around those stones were a lot of animals of all sorts; small fish, crabs, shells, sea slugs… I use a full face snorkel mask, so I don’t have a snorkel in my mouth but breath normally. Often I wasn’t even swimming, but standing breast-deep in the water and putting my head down. Fantastic! And you are so close without a separating glass wall. Sometimes little fish or crabs came to nibble on my fingers. some observations ( I just searched for the name of the beach, so there are also “above-water” photos.)