My first thought once I had dumped my rucksack in a locker in Verona train station was what the closest place to swim was. Cue a quick train journey 15 minutes away to a village called Peschiera del Garda. This is also the where you can get buses to gardaland, but keep walking down from the station at Pescheira and taking the left fork after you arrive at a sort of a moat you enter the small town. Which is in an old square fort with giant walls ringing the city surrounded by the aforementioned seawater moat. The town is small, quaint & cute, making it the perfect place to eat or stop for gelato once you have bypassed all the little (touristy) shops. Once I had seen the centre, I went back out past the pier (after admiring the beautiful blue of the lake and debating whether I should just dive in right there to escape the heat) out the fort walls and along the new pier/marina to a small concrete ramp that was used for a beach and submerged myself finally in the cool fresh water. I am sure there were other better beaches along the shoreline, but my priority was getting into the water asap!
The train from Verona takes only 15 minutes, costs about €3 so it is worth it to go for a day. If you are happy staying and relaxing by the lake or renting a boat to take out onto the lake, I preferred Peschiera to Desenzano. From here you can also take a bus to Sirmione which we intended to take when we returned to Peschiera on Sunday, although Sunday buses go only once every hour so plan in advance. They have one or two museums, mainly about the lake and fishing, at the time an andy warhol exhibition and its nice to walk along the sloped earth ring around the city if you can stand to climb the thirty stairs in the heat. Renting a bike to cycle along the shores of the lake might be nice option if you can find a rental store closer to the station, we walked until the bus finally arrived to take us to Sirimione.