Seeli is a small lake located in the municipality of Seelisberg, Canton Nidwalden, Switzerland. Often referred to as Seelisbergersee (Lake Seelisberg), it is situated at an elevation of 1,029 meters (3,376 feet) above sea level, nestled on a high plateau overlooking Lake Lucerne (Vierwaldstättersee).
Seeli is a popular destination for swimming, hiking, and other recreational activities. The lake is surrounded by forests and meadows, offering scenic views of the surrounding mountains. A lido provides facilities for swimmers, and boat rentals are usually available. The area around Seeli offers numerous hiking trails of varying difficulty, making it attractive to both casual walkers and more serious hikers.
Historically, the area around Seelisberg, including Seeli, has been significant for its role in the founding of the Swiss Confederation. The Rütli Meadow, where the Oath of Rütli is traditionally said to have taken place, is located nearby.
The village of Seelisberg, accessible by funicular from Treib on the shore of Lake Lucerne, provides access to Seeli and the surrounding area. The lake is also accessible by road.
Seeli (Seelisberg) is considered a natural landmark of the region and contributes to the area's tourism and recreational value.