Walk up to the green marker, and you will get an option to interact with it to start the task.
For the Cargo Ship robbery, you have three mandatory and one optional task.
Task 1: Bolt Cutters
In this task, you need to steal the bolt cutters from the marked site. You will see a yellow highlighted area on your minimap. The bolt cutters can be anywhere inside this area.
The most common building with bolt cutters is the long warehouse.
You might not be able to see the bolt cutters at first since it can be quite dark if the mission is at night time. But they are always on a table or a shelf inside the warehouse.
When you get closer to the bolt cutters, they are automatically located and highlighted on the map with a green duffle bag icon.
Once you grab the bolt cutters, some workers around the area will start to attack you, and you will get a 2-star wanted level.
Lose the cops and deliver the bolt cutters to your Salvage Yard to complete this task.
Task 2: Boat
In this task, you need to steal a boat from a storage facility.
When you get inside the storage facility, you will find a lot of enemies protecting the boats.
Once you get a notification about using one of the pickup trucks to hook onto a trailer carrying a boat, two more enemies will spawn behind you and approach you from the same location you came in from.
Once all the enemies are defeated, get into one of the pickup trucks and back it into one of the trailers carrying the boat. It will automatically hook to the trailer.
When you exit the storage facility, deliver the boat to your Salvage Yard to complete the mission.
The boat is needed to get to the cargo ship during the robbery. However, there is an easier method we will use to get on the cargo ship and also complete one of the bonus challenges. More on it below.
We are only doing this mission as it is a mandatory pre-requirement.
Task 3: Flares
In this task, you need to steal a flare box. For this task, you can get a random location.
You will get a yellow highlighted site, and you're looking for a white flare box, which is somewhere in the middle of the highlighted area.
In the case of the docks (our location), the flare box was in the middle of the highlighted area on a stack of bricks.
If you get the beach as your location, you will find the box resting on the railing of a lifeguard tower.
Once you collect the flares, the surrounding workers will attack you.
Task 4: Masks (Optional)
The masks play zero role in the robbery. They are included only for the sake of just wearing the mask, which has become a part of the meta in GTA Online heists.
However, if you're still interested in purchasing the mask and completing this task, you can head to the Vespucci Beach mask shop.
Purchase any mask set, and it will be registered as completed.
With the initial tasks completed, you are now ready to proceed to the more involved Planning Work missions.
