There are a total of 18 river power plants on the Danube which produce energy by impounding the water and making use of the river's slope. Inland vessels can negotiate the resulting differences in height along the course of the Danube by locks. Such locks can consist of one or more (usually two) lock chambers. 14 of the 18 locks on the Danube feature two lock chambers, thus enabling the simultaneous locking of upstream- and downstream-headed vessels.

Due to the high slope of the Upper Danube there are a total of 16 power plants with locks between Kelheim and Gönyű. On the Middle and Lower Danube there are only two locks at the Iron Gate, a gorge cut by the Danube through the Carpathian Mountains and forming the border between Romania and Serbia. The latter two locks are also the largest on the Danube: The Iron Gate I and II locks (river-km 942.90 and river-km 863.70/862.85) each have two lock chambers 310 m long and 34 m wide, which are located on the right and left banks. The lock chambers on the right bank (Ðjerdap I and II) are maintained by Serbia while those on the left bank (Portile de Fier I and II) are maintained by Romania.

Lock	Country	River-km	Lock chambers           L x W (m) | No.
Bad Abbach	DE	2,397.17	190.00  x  12.00  |  1
Regensburg	DE	2,379.68	190.00  x  12.00  |  1
Geisling	DE	2,354.29	230.00  x  24.00  |  1
Straubing	DE	2,327.72	230.00  x  24.00  |  1
Kachlet	DE	2,230.60	226.50  x  24.00  |  2
Jochenstein	DE/AT	2,203.20	227.00  x  24.00  |  2
Aschach	AT	2,162.80	230.00  x  24.00  |  2
Ottensheim-Wilhering	AT	2,147.04	230.00  x  24.00  |  2
Abwinden-Asten	AT	2,119.75	230.00  x  24.00  |  2
Wallsee-Mitterkirchen	AT	2,095.74	230.00  x  24.00  |  2
Ybbs-Persenbeug	AT	2,060.29	230.00  x  24.00  |  2
Melk	AT	2,038.10	230.00  x  24.00  |  2
Altenwörth	AT	1,980.53	230.00  x  24.00  |  2
Greifenstein	AT	1,949.37	230.00  x  24.00  |  2
Freudenau	AT	1,921.20	275.00* x  24.00  |  2
Gabčíkovo	SK	1,819.42	275.00  x  34.00  |  2
Ðjerdap / Portile de Fier I	RS/RO	942.90	310.00* x  34.00  |  2
Ðjerdap / Portile de Fier II	RS/RO	863.70+    862.85	310.00* x  34.00  |  2

* The Iron Gate I and II lock chambers (RS/RO) as well as the right lock chamber at Freudenau (AT) all feature a double-chamber layout.

To accommodate the different water levels of the Danube and the Black Sea, the Danube-Black Sea Canal has two lock facilities with two chambers each: at Cernavodă close to where it branches off from the Danube (canal-km 60.30) and further towards the Black Sea at the beginning of the canal at Agigea (canal-km 1.90). All of the lock chambers are 310.00 m long and 25.00 m wide.

The northern arm of the canal (the Poarta Albă-Midia Năvodari Canal) also has two lock facilities. One is located at its beginning near the Midia-Năvodari refinery (canal-km 1.50), and the second one is situated at canal-km 11.50 near Ovidiu. Both facilities feature two lock chambers of 145.00 m length and 12.50 m width.

Each of the locks at the 16 barrages of the Main-Danube Canal has one lock chamber with a usable length of 190.00 m and a width of 12.00 m. The 16 locks are remote-controlled by four remote control centres.