The eastern coast is washed by the North Sea. The western coast is washed by the Atlantic Ocean. There is the Isrish Sea between Ireland and Great Britain. The southern coast is washed by the English Channel or La Manche ("la manche" is a French word which means "a sleeve") and the Strait of Dover or Pas de Calais.
All seas around Britain are shallow and are good for fishing.
GB has many rivers but they are not very long.