To cross a stream, street or valley (wherever the delay attributable to a flight of locks at either side could well be unacceptable) the valley is often spanned by a navigable aqueduct – a famed illustration in Wales would be the Pontcysyllte Aqueduct (now a UNESCO Planet Heritage Website) https://canal-infantil99876.dbblog.net/10326257/rumored-buzz-on-canal-infantil