In the location's words:

Okay, not a classic outdoor pool, but absolutely worth mentioning: the Ricklinger Kiesteiche are THE destination for anyone who wants to swap outdoor pools for the great outdoors. Swimming, sunbathing, picnicking - everything that's fun is allowed here (except barbecuing, sorry!).

Our suggestion: start with a day of swimming at the gravel ponds and then take a short bike ride along the banks of the Leine towards the city center.