1. Rescue hostages:easy, medium, hard 
2. Disarm bridge bomb: medium hard 
3. Disarm engine room bomb: medium, hard 
4. Plant tracking bug on helicopter: easy, medium, hard 

You begin the level by quietly docking at the frigate via a small motorboat. Walk up to the man deck using a lone stair case. Turn left once you're at the main deck, and make your way to the second staircase you see. Walk up the stairs, open the door. Go the hallway's end, where there's a door in front of you and one to the right. Enter the door on the right and take out the guard holding a hostage. Kill the guard closest to the hostage first, because he's most likely to kill the hostage. There should only be two guards in that room; after you kill them, go to the only other door in that room. A second hostage is there, so aim and drop his captors, being careful not to blow up the amazingly sensitive equipment. 

Leave that room, walking right along the hallway. Walk down the set of stairs, then take a right. The first room on the right holds a gunman on the far right side. Take him out (duh). Retrace your steps out of that room. Continue through the hallway to a set of stairS next to another turn in the hallway. This is kind of cool: shoot the guard at the bottom of the stairs first; the other guard won't even notice all the racket, and then kill the deaf guy at the top of the stairs, collect his gun, and descend the stairs. 

Now do a 180 degree turn, walk a few short steps, and enter the room on the right: It's the engine room. There are a handful of guards in it, about four to five. Shoot the ones all on top of the walk, descend the stairs and at the bottom and at the far side of the room, you can see a hostage standing, looking as if he were being held at gunpoint. Funny that, he is. Walk carefully toward him and, after clearing ventilation shaft on the left, you'll see the assassin. Make sure to add extra lead, when you kill him. Be stealthy, or the assassin will kill the hostage (this goes for any of the hostage situations). If you turn 45 degrees to your right another guard is standing there waiting to kill you. Turn around, and... (that's right) kill him. One more should be floating around down there, so remember to kill him dead too. 

Now, you're on your way to disarming the computer. Ascend the stairs and look across the room. If there is another guard there (and there may be), well...kill him! You should see a computer monitor against the wall. Before approaching it, check to make sure no once will shoot you, and then switch to the bomb defuser located via your handy watch. Diffuse the bomb by pressing B. There's only one hotwired computer left. It's upstairs. Leave the engine room via the door you're closest to. Follow the hallway, passing a staircase, to a door leading to a control room with a hostage in it. Kill the aggressor. Beyond this room is a hallway with yet another hostage. Dispatch of this bad man and take his nice gun. Retrace your steps, and ascend the stairs you found outside the machine room. 

Retrace your steps all the way back to the very beginning, where you first entered into the ship. The hallway is the first one entered. When you enter into the hallway, a door across the ship will catch your eye. Go toward it and prepare to save one last hostage. Before you enter, you may be carrying a gun in each hand. Switch to one, whichever you feel comfortable with, but remember there are at least three guards in that room, and more who will enter when they hear your shots. Load you gun if it hasn't been reloaded. Make a special note to yourself that the assassin and the hostage will be in the center of the room. To the right, just out of site are at least three others. Shift to the left side of the door before you open it to get a much better angle on the assassin. Enter, shoot the guy nearest the assassin, then kill the other three or four. Remember not to kill the hostage who may get in your way once he's freed. Once everyone is dead, reload. Look for the control console with a little bomb on top of it. Diffuse the bomb. This will complete an objective in the medium and hard levels. 

You now need to find and place the tracker on the helicopter. Back up against the computer consoles. Look across the room: from left to right on the opposite wall, there are four doors. Take the door second from the left. Go straight through two doors, take a left, a right, and then continue on through the hallway, passing though two more sets of hallways. You should be able to hear the helicopter. The last door in that hallway leads to the copter. Go down the stairs, approach the copter, switch to the Tracker bug, and press Z. Now you just have to find a way out. 

Walk around the copter to other side of the ship where you'll see a long staircase, walk up it, through two doorways, and then descend a staircase. You'll be outside on the deck again, but on the correct side. Stroll forward to the giant missile, look across the deck, and eye a the narrow staircase descending to your motorboat.