context: Area - 750 thousand km² [2]. The greatest depth is 725 m [3]. More than 2/3 of the sea has a depth of less than 100 m; in the southern part - shallows (Dogger Bank and others). Large rivers flow in: Elba, Weser, Rhine, Thames. Main ports: Rotterdam, Amsterdam, Antwerp, London, Hamburg, Oslo, Bergen [3].
question: What is the depth of the North Sea?
answers.text: less than 100 m