Passaúna Park protects part of the Passaúna Basin west of Curitiba, including a large reservoir and stretches of green space around it. Trails, ecological areas, and a biological station make it more than a simple neighbourhood park.
The main reason to go is the view from the observatory, which looks across the water and surrounding landscape. It is a useful change of pace from Curitiba's better-known urban parks if you have extra time in the city.