Marius

If you have the money go for it!
It's extremely expensive for brazilians, but if you come from a country with a stronger currency there is no better place to eat seafood in Rio.
But you can eat as much as you want, it's a buffet.
And the quality of the food is incredible.
It's more a feast than a buffet they have. Awesome!
By the way, the map is wrong. It's not near any favela! It's actually by the beach!

A real nice restaurant in Rio de Janeiro, Zona Sul, between Copacabana and Leme. 50 meter to the beach by crossing the road.
The restaurant Marius looks a bit like an underwater cave. Very nice ambience, the waiters always pay attention and are very friendly.
The food is very good. You can choose between meat dishes or fish dishes. You also have a huge salad bar and buffet with oysters and other sea fruits.

For smokers you will find a cosy smoking lounge where you can enjoy a cigar or cigarette with a nice coffee.

The prices are relatively OK. They have a good wine card with a choice of the main wine regions of the world.

Try it.