The small lake Andromeda had mentioned turned out to be bigger than Hermione had expected, and after Andromeda told stories of Tonks" swimming nearly every day and sometimes transforming her nose and mouth to that of a fish, Hermione took to swimming as well. It helped clear her mind when she found herself too troubled by not hearing any news or having any idea what she was supposed to do. Having to just wait was horrible, and when Tonks finally arrived, she thought she would be able to breathe afterwards.