When you enter the fractal, first you need to kill 2 Veteran Bristlebacks, 2 Veteran Smogscales and 1 Veteran Bonebreaker. After you killed them, you need to move to the rock wall to kill the Champion Stonehead. Break his breakbar to kill it easily. After killing it, he will Fear you back and die in the mines. Use the cannon to clear out the mines to gain access to the next encounter.
Prestack boons on the Mistlock Singularity nearby.
Kill the ghosts to start the encounter.
Blast Black Peter the skeleton boss is kind of a DPS race. He starts spawning many minions by the end of the encounter so you can wipe easily. He spawns mines which you can blow up with the cannon on top. The boss periodically gains Swiftness Protection and Stability so removing it is priority and a key to kill him fast. He has a breakbar too so break that also helps.
Your objective is simple. You need to collect 3 treasures and carry them to the treasure chest at the end of the cave. There will be moving AoEs spawning enemies if you move into it. If you touch the treasure, you will gain a debuff that slows you down significantly, to move the treasure fast, throw the item at each other moving towards the treasure chest.
Superspeed overrides the slow inflicted by holding a treasure chest.
Here you have to get the chest onto the ship by throwing the treasure chest at each other, same tactic as before. You can use the Mistlock Singularity at the entrance to reset your cooldowns. If you happen to be in combat (you triggered the AoE circles) then just skip it and take it when you '/gg' before you fight Arabella Crowe (it is to reset mobs from the previous event and to start with no cd and fresh boons).
You need to get a chest again, now from one of the shores (random which one). Use same tactic as before, throw the chest across. There are 2 cannons each side of the ship, use it to clear mobs easily. After recovering the treasure the first mini boss spawns named Mad Jack Squall. During the boss there will be AoEs across the ship that blows players down the ship into the poisonous water. These AoEs cannot be ignored with Stability
You need to get the chest once again from one of the shores. Use same tactic as before, throw the chest across. Use cannons to clear mobs.
After recovering the treasure the second mini boss spawns named First Mate Calix. During the boss there will be a new mechanic that spawns AoE on the player furthest away from the boss, place this AoE outside the fighting zone. The knockoff mechanic from Mad Jack Squall is present as well. Kill him to start the next objective.
It will be a point capture event, you need to stay alive long enough to kill all mobs coming from the two sides of the ship. Use the cannon to clear most of the ghosts. After the event is done, the main boss spawns.
/gg to reset mobs on the ship and use the Mistlock Singularity to stack boons. The two mechanics from before, the knockoff and AoE are present in this fight as well as a third one. It is an AoE placed on a player with a timer. If the circle fills, huge damage is dealt to the player, but you can split up the damage between players, to counter this mechanic simply stack in the circle to split up the damage dealt to each player. The boss will be teleporting around as well as spawning mobs every 10% health of the boss. Kill her to finish the fractal.