After Trevor decides to take the plans using a chopper and a submarine, the player needs to steal a yellow Submersible, which is hanging off the freighter located in the Port of Los Santos. To free the submarine, Trevor can sneak onto the ship and release the cables holding the submarine using an on-ship control panel. There is one guard that Trevor must either avoid or kill. Alternatively, Trevor can use a sniper rifle to take out the cables holding the submarine, which lets the submarine fall into the water. Either way, Trevor must then board the submarine and pilot it to a different part of the port. There, Floyd pulls the submarine from the water using a crane and places the submarine on a tractor trailer. Trevor and Floyd tie down the submarine, then together drive it to a port warehouse for safekeeping.
Retrieve the sub.
Go to the extraction point.
Drop the sub off at the warehouse.
Get out of the truck.
Gold Medal Objectives
Time - Complete within 08:30.
Skip the cutscene and take the boat towards south Elysian Island and then go towards Pier 400 and stay close to the surface to avoid underwater obstacles.
No Boarding - Steal the Submersible without boarding the boat.
Snipe the cables from land and dive into the water to obtain the Submersible.
This mission is the only heist set-up mission to appear in both Option A and Option B of a heist set-up.
This mission is one of the first instances in the game where Dolphins can be observed. Several will usually take interest in the Submersible, and can be identified by their calls.
It's possible to unhook the trailer from the Packer and grab a different truck to pull the trailer. However, during the Merryweather Heist, the same Packer used to pull the Submersible will appear instead of the different truck you used earlier.