Hemingway used to walk along the Seine.

You could walk the length of the Île St.-Louis, and then Notre Dame and Île de la Cité opposite you as you walked.

The bookstalls along the quais sold English books tourists left in their hotels.

He would walk when he as trying to solve a writing problem in his head. It was easier to solve it walking, or watching people do things they knew how to do, like fish. He watched people fish.

He didn't fish because he preferred fishing in Spain, he didn't have the tackle, or the time--fishing takes time, if you do it properly--but you could tell by what he said about the water and the time of day and the people fishing that he knew how to fish, he enjoyed it, he enjoyed eating fish he caught.

He knew an open-air restaurant, La Pêche Miraculeuse, where he would buy a very good friture with a wine that was a sort of Muscadet.