From the top of the Palisades, looking down on the IM courseMost of the New York Ironman race hovers around the Palisades, a 20 mile band of steep cliffs above the Hudson River. The run takes place on a hilly road at the base of the cliff and the bike loops around the top.
Described in this New York Times article, recently a huge section of cliff cracked off and slid towards the river. The rock slide does't affect the race course, but it did take place very close to one of the toughest sections of the bike ride: the NJ/NY state line. This is the highest point along the Palisades (over 500 feet) and triathletes will have to climb up to it 4 times.
Also of note, Ranger Station hill (miles 2-3) has been repaved. All of the cyclists and triathletes can thank Ironman for that!