FROM TOKYO TO PARIS TMZSports.com
Katie Grimes admittedly had some things other than her opponents on her mind before hopping into the Seine River at the Olympics earlier this month ... telling TMZ Sports she was actually "nervous" about the water's cleanliness.
Of course, the E. Coli levels of Paris' famed body of water were a huge talking point in the leadup to the Games ... as the city dumped a fortune into making sure it was safe enough for athletes to swim in during the Olympiad.
On race days, officials deemed it was all OK for competitors .