In a tiny mall on the river walk, you'll find Rio Gelato. We actually sought this out due to the tripadvisor reviews and for once we were disappointed.
Only a small selection of flavours and the texture of the ice cream was very odd, it crumbled when you tried to scoop it up with a spoon. Very strange.
Service was friendly and prices were OK but I wouldn't go back. I just didn't think it was 'proper' gelato.