Sky Pool
The Sky Pool straddles two tower blocks, while families below look up excitedly knowing they could never afford to swim there.

While I was there a man seemed to be quite happily swimming backwards and forwards, doing laps between the buildings.
Which seems a better idea, using it for exercise, rather than the original purpose as a soggy shortcut between skyscrapers*.
* This bit was made up
Wikipedia says itβs only for residents, no day passes available, so for a more accessible way to cool down head to Elephant Springs, or take a swim in Greenland Dock.