You will not be able to explore the entire map from the get-go. The bridge connecting Founder’s Island to Miagani and Bleake will be raised for almost the first half of the main storyline. To access the third major area on your map, you will need to find a way to lower the bridge to get your Batmobile across into Founder’s Island in Batman: Arkham Knight.
How to lower the bridge in Batman: Arkham Knight
You need to destroy the defense grids on Founder’s Island to lower the bridges to both Miagani and Bleake in Batman: Arkham Knight. This objective is part of the main story mission City of Fear which you have to complete about 57 to 60 percent before the Batmobile can cross into Founder’s Island.
After locating and protecting the first giant tree on Miagani Island with the help of Poison Ivy, you need to head to the Panessa Movie Studios to analyze the Arkham Knight’s forces before you can enter the Founder’s Island.
This is where you will first meet with Robin and learn that you need to hijack a drone on Founder’s Island to get rid of the Island’s defense grid before you can lower the bridge to Founder’s Island and bring the Batmobile in.
Glide onto the relay drone and examine it
Reach the raised bridge to Founder’s Island near the west end of Miagani Island. Eject out of your Batmobile and glide or grapple to the railings above the bridge. From here on, you will have to traverse by gliding.
Once you approach the designated area, you should be able to see a drone flying around that you need to hijack. Glide on top of the drone from a high point to examine and hijack it. This will unlock the Drone Hacker feature for your remote Hacking Device.
Destroy the Arkham Knight’s radar network
From this point, your only choice is to sneak around without getting detected as this area is swarming with armed enemies, drones, and sentry guns that will rend you to shreds before you can even drop a smoke pellet. Luckily, you just acquired the Drone Hacker that can blind an enemy drone for one minute.
Use the Remote Hacking Device to temporarily blind the drone near you and take out the first radar using Explosive Gel. This will cause Arkham Knight to deploy additional reinforcements to protect the second radar. You will find a tough fight before you can destroy the second radar. Make sure to use your gadgets to make the battle easier.
Once you have cleared the enemies, interact with the electrical panel to gain access to the second radar. The second radar is guarded by a pair of sentry guns, use the RHD to blind one of the guns for 15 seconds and take out the second radar.
Lower the barriers protecting the missile launcher
After you have taken care of the radars, head east to the missile launcher. Take down the armed enemies present there. Now you need to disable the missile launcher’s protective shields. To do this interact with the computer in the middle level of the building. Doing this will also lower all three bridges to Founder’s Island in Batman: Arkham Knight.
Now you can remotely control the Batmobile and bring it into the Founder’s Island but be prepared for tough vehicle combat as the Arkham Knight will deploy Cobra Tanks to protect the missile Launcher.
Destroy the missile launcher
As soon as you bring the Batmobile into the Founder’s Island, you will need to destroy five Cobra Tanks before taking a shot at the missile launcher.
Taking on the Cobra Tanks head-on is nothing short of a death sentence. These monstrosities can rip the armor on Batmobile like wet paper. Start by sneaking behind one of the Cobra Tanks to analyze it for weaknesses. If you get spotted, exit the battle mode and step on the gas to run away.
Once analyzed, you can take out the tanks by sneaking behind one and firing a 60 mm cannon round to its weak spot. Do this for each of the tanks one at a time while making sure not to get spotted by the others.
Once the tanks have been dealt with, reach the designated area to raise the ramps. You will be interrupted by the arrival of Arkham Knight and his lackeys but once you have dealt with them you will be able to raise the ramp and destroy the missile launcher with your Batmobile.
