Venta Rapid (Latvian: Ventas rumba) is a rapid on the Venta River in Kuldīga, Latvia. This is the widest rapid in Europe – 249 metres (817 ft) and up to 270 metres (886 ft) during spring floods. Its height is 1.80–2.20 metres (5.9–7.2 ft) and it changes depending on the water level in the river. It also features the widest waterfall in Europe. It's 110 meters wide, but only two meters high. In the stone canals are carved. They were used to catch salmon and sturgeon. If the fishes didn't make the jump up the river they would be swept back by the current, into the canal and be caught in hanging baskets.
From - http://en.wikipedia.org/wiki/Venta_Rapid
Check out this virtual tour also - http://virtuallatvia.lv/Tours/Kurzeme/Kuldiga/VentasRumba/flash/VentasRumba.html