[eesmith]

With Google Maps I found a ferry on the Swedish lake Hjälmaren, between Vinön and Hampetorp.

https://sv-m-wikipedia-org.translate.goog/wiki/Vin%C3%B6lede... says the route is 5km long and takes about 16 minutes.

Wikipedia says the lake is 483 km², while Lake Champlain is about 3x bigger at 1,331 km².

From Google Street View it seems the mainland is visible for nearly every direction.

Oh! I found another ferry, a car ferry from "Boheden, 956 93" to "Sandudden, 956 93 Överkalix", according to Google Maps. The lake Djupträsket is 8.68km² and the ferry is a few hundred meters.

And one between Sund and Jarenleden, on the lake Stora Le, 131 km² but it's narrow and the ferry is only about 600m.

Sweden has a LOT of lakes, and most of them are narrow. I assume they were made by glaciers? I found those two ferries by looking for two roads ending on opposite sides of a lake.