Italian Lakes. The Italian Lakes are a group of large lakes lying on the south side of the Alps, in the basin of the river Po and the Mediterranean Sea. As their name suggests, they are essentially located in northern Italy; however, they are also partly located in southern Switzerland. They are all glacial lakes that formed after the retreat of the glaciers at the end of the last ice age. The group is composed of : Lake Orta, Lake Maggiore, Lake Varese, Lake Lugano, Lake Como, Lake Iseo, Lake Idro and Lake Garda. The three largest are all well over 100??km2; they are: Lake Garda, Lake Maggiore and Lake Como.