Drop down and flip around to find this marker. When Ivy's vines overrun the Botanical Gardens they will create a hole by the main entrance in the Glasshouse Entrance area. Shimmy over and pull yourself up to find a small nook with a Chronicle of Arkham marker. You can Line Launch to it from the middle area - you'll have to climb a bit to get there (cut down the suspended walkway in the south with a Batarang to get to the highest area - you'll need the line launcher to cross to the center area). In the northwest corner of the Abandoned Chamber, at the top of the room, there's a ledge you can leap to and get a hand hold from the middle area. Crouch and follow it south to the Riddler Trophy. In the Abandoned Chamber, drop to the ground level and hop down into the stream of water in the northwest corner. In the Flooded Corridor, cross the long trench on the west side of this room with your Line Launcher. Crawl into the shaft and follow it back to a trophy.
Mine it with Explosive Gel and blow it up to reveal a ventilation shaft. In the Botanical Glasshouse, search behind the base of the fountain for a destructible wall. Take the north path for a Riddler Trophy. In the Flooded Corridor, after you can traverse the water safely, cross it and enter the vent near the collapsed portion. Pull this panel down with your Ultra Batclaw and Line Launch over to the platform with the marker on it. In the Titan Production facility, look for a breakable wall panel across the wide gap on the east side of the room. Batman: Arkham Asylum The Riddler's Challenge «