Which Is The Longest River In Britain. The river great ouse is a river in the united kingdom, the longest of several british rivers called “ouse”. Among these rivers, the volga river is considered as the longest european river, flowing for a distance of 2,294 miles.
3 river trent 297 km. The river thames is the deepest river in the uk. River towy is the longest river that flows entirely within the borders of the country.