It is very interesting and realistic for the engineers to build canal on land area or with rivers, that a oceanic units can go through. --unsigned
In Freeciv 2.1.4, I used my engineers to change mountains to grassland. First they removed dirt (transforming mountains to hills) and then they removed more dirt (transforming hills to grassland). It seems realistic. However, I have never used my engineers to build canal.
The Terrain part of the manual says that engineers may transform swamp to ocean. If I wanted to build canal through plains or grassland, my engineers would have to plant some trees (mining plains or grassland to forest), let in some water (mining forest to swamp) and then dig the canal (transforming swamp to ocean). The swamp must already have an adjacent ocean square. --Kernigh 23:24, 23 June 2008 (UTC)