In 2015, the Guerlédan Lake was drained for maintenance of the hydroelectric dam. The vestiges of a hidden landscape were revealed, including the Nantes-Brest canal, houses, trees and submerged slate quarries.

In 2015, the Guerlédan Lake was drained for maintenance of the hydroelectric dam. The vestiges of a hidden landscape were revealed, including the Nantes-Brest canal, houses, trees and submerged slate quarries.