Must have completed:Pirate's Treasure and Rum Deal
42 agility, 45 crafting, 50 smithing, 40 ranged.
If you have not completed Ghosts Ahoy: Ectotokens and an amulet of ghostspeak, or some coins to charter a ship (amount depends on boarding location).
2 Quest points
7000 Smithing, Crafting and Agility experience
10,000 coins (only if you speak to Bill Teach after the quest)
Access to Mos Le'Harmless
Access to kill cave horrors
Book o' piracy
Charter ship prices are halved
2 Treasure Hunter keys and 2 Hearts of Ice