In a pool there is little to see; swimming in open water tears away the blinkers, and suddenly you have a world of visual stimulus, just as you do when out on your bike or running through the countryside.
…
The perfect swim anywhere you could choose would be in a tropical sea, from beach out to an island and back, looking down as you stroke to see stingrays. Swimming there, surrounded by fish, warm salt water keeping you buoyant, you are alone with your thoughts yet entirely happy with them. There is nothing to compare with that.

— Alastair Brownlee, in Swim, Bike, Run: Our Triathlon Story by Brownlee, Alistair; Brownlee, Jonathan

After 4 days of heavenly swimming around islands in the warm Mediterranean, I’m dreading going back to swim in the pool at Surrey sports park. Couldn’t agree more with you, Al!