Can one who goes to the mikva daily before davening or at least before Shabbos, do so by going for a swim in a lake next to him during the Nine Days? Is there a concern of Ma’aras Ayin. (people watching may think that one is going for a prohibited swim)?

Horav Aharon Miller’s Shlit’a opinion is that it is permitted only if he goes in and out as necessary, but does not stay for a continued swim. Since he is going in and out immediately without swimming, there is no concern for Ma’aras Ayin.