Paddle boating on the Guadalquivir River
The Guadalquivir River famously splits the city of Seville in two parts. I recommend renting a paddle boat.
From a paddle boat you can catch some rays, get a great leg workout and even jump in the water all in one afternoon. The boats hold up to four people and generally come with large sun umbrellas. They’ll only cost you a handful of Euro per hour and are for rent on the southeast side of the river (right where all the big barges park.)
Warning: It’ll be hot! Bring water. And the water will be gross! (i.e. very green and probably unsanitary) Enter with caution.