Take some photos of Octavio's tar pumping scheme.
After a chat with Bentley, Octavio will start tar-polluting a nearby fountain. Take a picture with the binocucom, and move on. Keep going until he reaches the second tar pump, which is near a bridge. After he finishes polluting a birdbath, keep shadowing him. Near his opera stage, you have to board a boat to get a picture of his water wheel pollution. The last switch is also along the bay, and you have to board a boat to get a picture of him polluting an aquarium. Then, you have to go to the Ferris Wheel. Once you arrive there, latch on to Octavio's car and eavesdrop on his conversation with Don Giovanni. After Bentley hacks the control panel, the structure will fall, then it's Job Complete!
Note: You must stay out of Octavio's line of sight the whole time.