Everywhere in the world, this body of water is known as Lake Geneva.
Except in Geneva and the surrounding cities. To the locals it's known as Lac Léman.
I could understand if people in Geneva blatantly called it Lake Geneva in spite of everyone else, like people in Georgia who still talk about the War of Northern Aggression. But even the locals call it Lac Léman. Seriously, people, where's the team spirit?
I'm not sure who Léman is. But this is a wasted branding opportunity. Google "lac leman" and the top hit is "Lake Geneva."
To me that's like the whole world calling Lake Michigan "Lake Michigan" while the denizens of the Wolverine State insist, "Oh no. It's actually Lake Churbit."