The Schwarzenberg Navigation was a system of canals incorporating navigable sections of some natural waterways which linked the River Vltava with the River Danube. The link between the two rivers, the first of which flows north to the Baltic, the second eastwards to the Black Sea, had been contemplated in the 14th century, but was only realised at the end of the 18th century, when the initial motivation was the prospect of supplying Vienna with firewood from the Šumava forests. The system incorporated part of the River Mŭhl, and it was only in 1789 when the exclusive rights of the Bishops of Passau to float timber on the river came to an end, that the planned navigation became feasible. It was planned by Josef Rosenauer (1735-1804), an employee on the estates of the Dukes of Schafenberg. The first logs were floated in 1791, and the first phase of the waterway with a total length of 39.9 km was completed in 1793. A second phase from the Jeleni river towards the Bavarian border with a 419 m long tunnel at Jeleni was built in the early 1820s, creating a system 89.7 km in length. The waterway was modified after 1850 to carry logs for building up to 19.5 m long, rather than the shorter lengths used for firewood, and trade northwards along the Vltava to Prague, Saxony and north Germany flourished until 1892, when a railway was opened along the same route. Only short sections of the waterway were used in the 20th century, although much of its course remained.The museum at Chvalšiny, 22 km south-west of Český Budĕjovice displays ancient documents, engravings, photographs and artefacts concerning the history of the navigation and the woodmen of the Šumava forests who provided it with its trade. The museum is located in the former town hall a few doors away from the birthplace of Josef Rosenauer, who is commemorated on a plaque.