Llyn Padarn is a natural freshwater lake situated in Snowdonia National Park, North Wales. It is located between the towns of Llanberis and Bethesda, and it is one of the largest and deepest lakes in North Wales, with a surface area of around 2.5 km² and a maximum depth of approximately 94 meters.

The lake is a popular destination for outdoor enthusiasts, with a variety of activities available, including kayaking, paddleboarding, fishing, and swimming. The lake also has a scenic path along its western shore, which offers stunning views of the surrounding mountains, including Snowdon itself.

Llyn Padarn is also known for its diverse wildlife, with various species of fish, birds, and mammals living in and around the lake. The area around the lake is a designated Site of Special Scientific Interest (SSSI) due to its unique geology, which includes rare rock formations and fossils.

In addition to its natural beauty, Llyn Padarn has a rich cultural history, with evidence of human activity dating back to the Neolithic period. The area around the lake contains a number of historic sites, including the remains of a Roman fort, the ruins of a 13th-century castle, and a 19th-century slate quarry. The lake is also home to the Llanberis Lake Railway, a historic narrow-gauge railway that offers scenic rides along the shore of the lake.