Groß-Gleinicker See has two official public bathing spots and the fine and sunny sand beach on the northern bank of the lake make it absolutely recommendable. Everything is a little more peaceful here than on the southern bank. However, also here you will find families with children bathing and swimming, often with floaties.
If you prefer it calmer and with a bit more shade, you will find some secluded coves along the northern bank which can serve as inofficial bathing spots. A little path on the height of Seepromenade 61 will lead you to these hidden coves.