This beach is a fantastic spot for swimming in the lake. Just be aware that the sand only goes up to the waterline, so you'll be walking on pebbles to reach deeper water. However, the diving boards and platforms near the shore make it worth it. There's also a nice restaurant on site. The small admission fee is definitely worth it. Just a heads up, parking is extremely limited so it's best to arrive early to secure a spot.
The Badi is lovely and not too far from Zurich. It has a diverse international crowd. There are fantastic kiddy pools, water slides for all levels, a diving platform, and a sunbathing area. The sandy beach is perfect for kids to play on. The snack bar offers a good selection of food, drinks, and ice cream. The changing rooms are spacious and clean. Just be aware that parking can be limited during peak times.