Riddler Challenge Water. Specifically the part in the gif at the top of this article. Use your batclaw to grab the trophy from the cranes hook.
After that return to the batmobile and drive back up. Batman_arkham_city_riddler_challenge_guide_30m_over_water 416 Batman Arkham City Riddler Challenge Guide 30m Over Water as the criminal organizations run wild seeking to fill the void left by the death of the Joker. Then grapple toward land until you align both parts of the question mark.
The next Riddler trial takes place in Gotham Casino.
Specifically the part in the gif at the top of this article. View Full-size The red and white tiles can toggle crushing floors left but you wont be able to control the green ones right. A little ahead you will come across a door named Balancing Act. Find the garage gate drive inside and take the elevator into the underground.