Sweden has many waterfalls and rapids, one of the rapids is shown on this stamp, it shows us also the aqueduct across the rapid on the Dalands Kanal near Håverud. https://en.wikipedia.org/wiki/Dalsland_Canal
The aqueduct was built in connection with the canal between 1865/68. The aqueduct is 32,5 metre long and has the form of long u-shaped steel gutter across the rapids.
The vessel passing the aqueduct is not identified I believe it is a stylized small passengership. There are three shipping companies that transport passenger and pass Håverud but the ships they are using don’t fit the bill.
The bridge in the background is the road bridge.
Sweden 1968 40 ore sg ?, scott?