Lake Iseo or Iseo lake (US: ee-ZAY-oh; Italian: Lago d'Iseo Italian pronunciation: [ˈlaːɡo diˈzɛːo]; Eastern Lombard: Lach d'Izé), also known as Sebino (Italian: [seˈbiːno]; Latin: Sebinus), is the fourth largest lake in Lombardy, Italy, fed by the Oglio River.

It is in the north of the country in the Val Camonica area, near the cities of Brescia and Bergamo. The lake is almost equally divided between the provinces of Bergamo and Brescia. Northern Italy is known for its heavily industrialised towns and in between there are several natural lakes. Lake Iseo retains its natural environment, with its lush green mountains surrounding the crystal clear lake.

There are several medieval towns around the lake, the largest being Iseo and Sarnico. A notable tourism sector has emerged. A road has been carved into the side of the mountains that circumnavigates the entire lake. In the middle of the lake there are Montisola island, Loreto isle and San Paolo isle (which compound the Monte Isola municipality). There is easy access via the regular running lake ferries.

The Floating Piers, an art installation by Christo and Jeanne-Claude, was open to the public at Lake Iseo for 16 days in June and July 2016. The Floating Piers were a series of walkways installed at Lake Iseo near Brescia. From June 18 to July 3, 2016, visitors were able to walk just above the surface of the water from the village of Sulzano on the mainland to the islands of Monte Isola and San Paolo. The floating walkways were made of around 200,000 polyethene cubes covered with 70,000 m² (750,000 sq ft) of bright yellow fabric: 3 km (1.9 mi) of piers moved on the water; another 1.5 km (0.93 mi) of golden fabric continued along the pedestrian streets in Sulzano and Peschiera Maraglio.

After the exhibition, all components were to be removed and recycled. The installation was facilitated by the Beretta family, owners of the oldest active manufacturer of firearm components in the world and the primary sidearm supplier of the U.S. Army. The Beretta family owns the island of San Paolo, which was surrounded by Floating Piers walkways. The work was a success with the Italian public and critics as well.

Since 2018, the northern portion of the lake (called Alto Sebino) has been part of the UNESCO World Biosphere Reserve of "Valle Camonica - Alto Sebino".