It is significant for the ruins of one of the 19th century's largest ice harvesting factories and the occasional outflow of water in two directions.

The lac de Sylans fills part of the Nantua water gap, which was formed during the last glacial era.

The formation of the lake itself is much more recent; it is the result of the collapse of the cliff on the Northern side of the valley a few centuries ago.

Later when the Haut-Bugey railway line was opened, 20 to 30 wagons loaded with 10 tonnes each departed every day of the summer for Paris, Lyon, Marseille, Toulon and even Alger.

On the south side the Haut-Bugey railway line, initially a regional line from Bourg en Bresse to Bellegarde, but rebuilt in 2010 to carry TGVs from Geneva to Paris On the northern side the A40 autoroute connecting Switzerland and Northern Italy (via the Mont Blanc tunnel) to France.