the river humber is a large deep water estuary on the east coast of northern england. it is formed by the river ouse and the river trent coming together. from here to the north sea (about 40 miles) it forms part of the border between the east riding of yorkshire on the north side and lincolnshire on the south side. the humber's only modern crossing is the humber bridge. at one time it the longest single-span suspension bridge in the world. now it is the fifth longest. before the bridge was built in 1981, paddle steamers were used to cross the mile long span.