Here are several ways to say that someone is going against the tide:
natare adverso amne
to swim, the stream being contrary
where amnis, amnis is a feminine noun for a torrent and adverso amne is an ablative absolute.
You could also use these ablatives absolute with similar meaning:
contrario amne
contrario flumine
and then you can say
contra currentem.
Seneca says that to fight against nature is the same as rowing against the water:
… remigare contra aquam.
These very words were recently used in a Papal tweet.
Teachers could take this short message and play with it in the classroom.
Students can express “going against the tide” in these and other ways.