The Devil's Channel—Čertovka in Czech—is a 740-metre man-made canal carved from the Vltava River in the 12th century to power grain mills on Kampa Island. The waterway earned its name from a notoriously ill-tempered washerwoman who lived beside its banks in the 19th century, though local legend prefers the story of a devil who dug the channel in a single night. By 1770, seven mill wheels turned along its length; three restored wheels operate today, fed by the same current that once ground flour for Prague's Old Town bakeries. Prague boat tour Devil's Channel routes pass beneath the southern arch of Charles Bridge, where the canal splits from the main river, and wind through a corridor barely twelve metres wide in places. Stone embankments date to the 1600s, when the Nostic family fortified the waterway to protect their Kampa mills from spring floods. The Grand Priory Mill—now a museum—anchors the channel's northern entrance, its overshot wheel visible from Kampa Park. South of the Lennon Wall, the canal narrows further, hemmed by baroque townhouses whose cellars once stored milled grain. The channel's isolation made it a smuggling route during the Thirty Years' War and a refuge for dissidents in the 1970s, when underground musicians recorded in the cellars of Sovovy Mills. A 1784 decree by Joseph II standardized the canal's width to accommodate coal barges; iron mooring rings from that era still stud the embankment below Velkopřevorské náměstí. The waterway froze solid in the winter of 1929, allowing skaters to glide beneath the bridge arches for six weeks. Prague boat tour Devil's Channel tickets grant access to electric catamarans and traditional wooden vessels, both designed to clear the channel's lowest bridge with thirty centimetres to spare. The 50-minute circuit departs from Dvořák Embankment, follows the canal to its southern terminus at the Herget Brickworks, and returns via the main Vltava past the National Theatre. Spring snowmelt raises the water level by forty centimetres, submerging the lower embankment steps and accelerating the mill wheels to full speed.