Tokyo
I swim wherever I go in the world.
Most of the time I am indoors and look at the ceiling of the pool
area when I do the backstroke. (My local pool ceiling on the right)
When I am outside, I get to see the sky and the clouds, the hotel and the buildings next to the pool and often the city skyline. In Tokyo I have swum in one pool that was about 300 feet in the air, on the top floor of a building with a view of half of the City.