Way to unlock: You need to complete Main Missions 31 (Minisub) and 33 (Cargobob), and also develop Michael's pilotage skills (Additional mission: Flight School; it may turn out that also completing some other missions, reserved for Franklin and Michael. is necessary). While playing as Michael, wait for a message from Trevor. You can now go to Floyd' apartment (letter H on the world map).
Playable characters: Trevor, Michael, Franklin
Additional information: this heist is even more demanding than the jewel store job and puts even more stress on teamwork between the playable characters. The mission consists of three parts - transporting the submarine into the area of the of the Merryweather vessel, lowering the submarine and using it to locate the cargo, and return to the airport with the stolen cargo.
After you return to Floyd's apartment, watch the cutscene of the meeting of all the people involved in the heist. While playing as Michael exit the building and obtain any vehicle with the capacity of, at least three. Your first task is to reach the airport seized by Trevor, which is located in the central part of the world map, To the South-West of the Sandy Shores.
Take your seat aboard the cargo helicopter (Cargobob), fly up into the air and keep the helicopter hovering above the sub. Extend the hoist and catch onto the sub to start the process of transporting it.
Your destination is to the North-West of the island so, you are up for a long flight. Try and keep the chopper at a high altitude, thanks to which you will avoid knocking against a tree or a slope of the Chiliad mount. After you get into the region where the tests are conducted, decrease the flight speed and release the sub.
After you cut to Trevor select the phone from his inventory and access the Trackify app. You can now start submersing. Swim towards the sea bottom and follow the red dot that you can see on the smartphone's display. You need to keep in mind the fact that the entire process is going to take you some time, because the cargo that you are looking for is deep underwater -it has been shown in the screenshot.
In accordance with the received piece of information, approach the cargo, thanks to which it will automatically cling to the sub. Now, for a change, you will have to start resurfacing but, the good news is that you will not be bothered (for now) by anybody.
After the sub reemerges again take control over the chopper controlled by Michael. Hover on, the chopper, over the sub and use the hoist in the way that you have already learned, and fly back to the airport where you have started the entire operation.
Unfortunately, you need to come to terms with the fact that things will soon get complicated, because there will be helicopters, with Merryweather mercenaries onboard, to start pursuit after Michael's chopper. Cut to Franklin and start your fire at the enemy choppers, while remembering about the option to slow down time. While conducting fire, you need to change between the left and right machine gunner positions . Fortunately enough, you should be able to tell by the radar where you currently need to fly.
Towards the end of the mission, you will have to conduct fire from the rear part of the helicopter but, in this case this will not change much. Still, try to eliminate all of the threats. The last step is to return to the airport, while playing as Michael again - first detach the sub carefully, and then land. This mission will soon conclude, and the results are not going to be as satisfying as the people participating in the heist would have wanted them to be.
Rewards for completing the mission: none
Requirements for the completion of the mission in 100%:
- Salvager - You need to locate the sunken cargo within 2 minutes
- Time - you need to finish the mission within 14 minutes and 30 seconds. Fly towards the freighter in a straight line and, after you submerge, locate the cargo as quickly as possible and resurface with it just as fast.
- Show no Mercenary - You need to eliminate all of the mercenaries that chase you towards the end of this mission
- Weathering the Storm - you need to complete the chase, in the final part of this mission, within 4 minutes. As long as you will be eliminating the targets efficiently, you will do with a half of this limit.