Go to the "D" to meet Derrick. There will be a short cutscene showing Derrick pulling up in a boat. after the cutscence you will be in the boat with Derrick at which pount he tells you about the mission. Go to the blue dot on your map to meet Kim's boat. Follow Kim's boat with your boat. Attackers in black boats will soon enter from both sides. Use L1 to shoot the boats. Aim for the attackers inside the boats. At one point Kim's boat will come to a stop. You'll need to stand up using the triangle button and use the rocket launcher and take out an enemy helicopter. Once the helicopter and all of the boats have been destroyed follow Kim's boat to the dock to end the mission.