Doggerland was submerged by a tsunami formed in what ocean?
Doggerland:  It was probably a rich habitat with human habitation in the Mesolithic period, although rising sea levels gradually reduced it to low-lying islands before its final submergence, possibly following a tsunami caused by the Storegga Slide. Storegga Slide:  The collapse involved an estimated 290 km length of coastal shelf, with a total volume of 3500 km3 of debris, which caused a very large tsunami in the North Atlantic Ocean.
North Atlantic Ocean