Schwarzer See — known in Czech as Černé jezero, or Black Lake — is the largest natural lake in the Czech Republic and the biggest glacial lake in the Šumava (Bohemian Forest). Sitting at 1,008 metres above sea level with a maximum depth of nearly 40 metres, it is a place of striking beauty and a real highlight of any Šumava hiking trip.

The lake nestles beneath the steep northern face of Jezerní hora, which towers 320 metres above the water as the dramatic Jezerní stěna cliff wall. Its famously dark colour is not a trick of the light — it is the reflection of the dense forests that encircle it on almost every side. In autumn the surrounding woodland turns golden and fiery red, making the mirror-like surface look almost painterly. The lake freezes over between December and April or even May, with ice reaching up to 75 cm thick, transforming the whole area into a hushed winter world. In summer, water clarity reaches 4–5 metres depth, a testament to the lake's pristine condition.

• Železná Ruda town — red-marked KCT hiking trail, approximately 6 km northwest of the town, easy to moderate difficulty.
• Špičák saddle (Špičácké sedlo) parking area — yellow-marked trail combined with the educational nature trail NS Špičák – Černé jezero, shorter and easier option.

• The lake is part of the Černé a Čertovo jezero National Nature Reserve — please respect nature protection rules.
• A seasonal tourist train runs several times daily from Železná Ruda directly to the lake; it is wheelchair accessible.
• Accessible year-round, though winter trail conditions can be challenging.

The lake's mysterious atmosphere has inspired generations of artists — composer Antonín Dvořák and poet Jan Neruda both drew inspiration from its shores. Pollen layers on the lake bed have been accumulating for thousands of years, making it a remarkable natural archive of Šumava's history.