A Watery Grave

Background
Your objective for this quest is to kill a breton sea captain named Gaston Tussaud in the cabin of his pirate ship, the Marie Elena. The ship can be found in the Imperial City Waterfront District. There are two ships at the Waterfront, the Marie Elena being the western-most one with pirates patrolling near it, guarding it against any trespassers who dared to stray too close to the captain's quarters.

Walkthrough
If you simply walk onto the ship, the pirates will attack, although they are dispatched easily enough with moderate offensive abilities. What you can do, however, is jump on to the ship, and then run away, letting the guards deal with the pirates instead, leaving the path clear to Gaston Tussaud. The alternative method of entrance is to get on the stone path west of the ship where there are a bunch of crates lined up. The pirates are loading all of these boxes onto the ship. Walk up to the northernmost crate and you will be asked if you want to hide in the crate. Do so and the game will load you inside the ship. Another method of entrance to the captain's cabin is to jump from the dock onto the balcony of the ship and pick the lock, which could prove difficult for a character lacking in a high security score, as the lock is fixed at the very hard level. If you are able to pick the lock, the best way to fight the captain is to run out the rear door once he begins to fight you and swim to shore. The captain will just pace back and forth on the rear deck and you can shoot arrows with impunity.

The ship has two pirates already inside of it along with the captain. These pirates can be killed or sneaked past. The captain proves a tough fight for some, but if your health gets low, simply run around the table in his room and heal as you go. The captain shouldn't be able to catch you while circling the table. Alternatively, you can yield to him, from which you can then sneak behind him and use a sneak attack to do extra damage.


 * Note: An easier and quicker method to complete this quest is by running straight to the captain's cabin and killing the captain. Then run out and let the Imperial City guards take care of the remaining pirates.

Another way to complete this quest with very little difficulty is to hide inside the crate, then go up a level. Wait for the pirates to finish their conversation (it's quite funny given the context of the quest) when they finish go quickly back to where you entered the level and go as far back as possible (a detect life spell helps here) and wait for the pirates to pass you by. Then sneak past them to the hall where they were talking. You should see a small alcove on your left with a ladder. Take this ladder up directly to the capitan's cabin. Wait until around 10pm when the capitan goes to sleep and sneak attack him, he should now be dead or close to dead. If you're of a moderately low level, then an advisable strategy is to do small amounts of heavy damage, then yield and repeat. Once he's dead search his body for the capitan's key. If you position yourself correctly you should be able to open the capitan's chest as soon as you exit the looting menu. If not, no worries you can always return later. After you have the capitan's key simply run to the far side of the cabin near the table (don't forget the nirnroot) and exit through the back. The quest is now finished with only the captain dead and minimal effort on your part.

When the captain has been eliminated, two pirates will come down to check on the captain. You may either kill the pirates or hide from them until they leave. After they're dead or gone, you may search the room for loot (Gaston Tussaud's chest has two Flawless Pearls, a Flawless Emerald, and 100 gold.) or you can exit through the door you came in and leave the ship.

Note: It is easier to just run to the end of the dock(by the crate you get inside) and jump onto the rear of the ship picklock the door and attack the captain from behind and come out the same way.

Note that once the pirates and Tussaud are all dead, the ship basically becomes a free "house" for the player to use if they desire. The Captain's Chest does not respawn (confirmed on XBox360; GotY edition), so if you kept the key you are able to store your items in there. You can use the bed for resting, and the captain drops some rather fashionable clothes if the player wishes to take them.

Bugs

 * There is a glitch in this quest that can cause you to permanently lose your horse. If you choose to get on board the ship by hiding inside the crate on the dock, and if you are riding a horse when you accept the "hide in crate" option, both you and your horse will be loaded into the ship's cargo hold. This dooms the horse to be trapped within the ship forever. The horse cannot be rescued using fast travel, even after you have left the ship.
 * If you are on the PC, you can rescue the horse with the console command movetoqt which moves you and your horse to your current quest target. Make sure beforehand to select a quest with an outdoors target; if the target is indoors then your horse will be stuck there instead. Another way of rescuing your horse is to use the console command . Make sure your target code is an outside location, or else you will find you and your horse stuck inside another location. A third method is to open the command console, click the horse, close console, and once outside re-open the console and type  . The horse should appear at your location.