The Rhine–Main–Danube Canal (German: Rhein-Main-Donau-Kanal; also called Main-Danube Canal, RMD Canal or Europa Canal), located in Bavaria, Germany, connects the Main and the Danube rivers across the European Watershed, running from Bamberg via Nuremberg to Kelheim. The canal connects the North Sea and Atlantic Ocean to the Black Sea, providing a navigable artery between the Rhine delta (at Rotterdam in the Netherlands) and the Danube Delta (or Constanţa, through the Danube – Black Sea Canal) in eastern Romania. The present canal was completed in 1992 and is 171 km (106 mi) long.
From Bamberg to Fürth the canal follows the valley of the Regnitz, a tributary of the Main. From Fürth to beyond Roth it follows the valley of the Rednitz, a tributary of the Regnitz. It crosses the Frankish Alb mountains and joins the river Altmühl near Dietfurt. From Dietfurt to Kelheim on the Danube the canal follows the Altmühl valley.
The cross-section of the waterway is normally trapezoidal, with 31 meters width at the bottom, 55 meters wide at the water surface, 4 meters of water depth, and a side grade of 1:3. The channel is a Waterway Class Vb; the largest authorised vehicles are 190 m in length and 11.45 m wide. The channel in the Kelheim-bound Bamberg lock has a depth of 2.70 m. In the few sections with a rectangular profile, the width is usually 43 m.
The length of the canal is 171 km; the summit altitude (between the Hilpoltstein and Bachhausen locks) is 406 m above sea level. This is the highest point on Earth that can be reached by watercraft from the sea. Along the course of the canal are 16 lock with lifting heights of up to 25 meters, of which thirteen are designed to conserve water.
The height difference along the north ramp of the canal — from the Main at Bamberg to the crest attitude — is 175 m, with 11 locks. From the crest attitude down to the Altmühl at Dietfurt is a drop of 51 m in altitude, through three locks. The further difference in altitude of 17 m along the Altmühl, with two more locks, makes a total of 68 m for the south ramp. This means that the Danube end of the canal is 107.3 m above the level of the Main end.
The 16 locks are managed from four remote control centers (Neuses since 2007, Kriegenbrunn, Hilpoltstein, and Dietfurt from the beginning of 2007). These centers are manned with one (night shift) and two (day shift) employees. The locks were modernized from 2001 to 2007, replacing the outdated relay technology with computers and a PLC. The cost is approximately $ 1.3 million per lock.
The long-distance Challenge Roth triathlon, which is held annually in July, includes a 3.8 km swim in the Main-Danube Canal at Hilpoltstein. The canal is closed to vessel traffic during the race. An approximately 14 km-long section of the marathon route runs along the canal from the Hilpoltstein lock to the Leerstetten lock.