Lake Garda is a tourist area particularly suited to the needs of children. In the south shore the water is so low that you can leave your children alone to splash in the water. The north shore is more interesting for water sports lovers.
The four beaches in the south-east of the lake are particularly suitable for children: Punta Cornicello in Bardolino (small but with trees and a playground), the beach at the port of Pacengo (flat beach of coarse sand, with some tree, bar and showers) as well as the beach of Santa Maria di Lugana opposite to the peninsula of Sirmione (a large grassy park with games, possibility to rent pedal boats and parasols).
The great Sabbioni beach on the north shore at the heart of Riva is suitable for adults, because the water is deep (pebble beach, with an artificial island for swimming and trees).
In Riva, there is a large number of playgrounds for children. You'll find them listed in the map distributed free at tourist information office.