Go to your faction’s main city
Take the portal to Vashj’ir from the Cataclysm portal room
If you do not see the portal, accept the Vashj’ir intro quest from the Hero’s Call Board or Warchief’s Command Board
Follow the quest chain until you are sent to Vashj’ir
Use the underwater transport from your faction’s quest hub if you are already on the chain
If you are on a low-level character, level up until the Vashj’ir zone becomes available
Alliance: travel from Stormwind Harbor after starting the quest chain
Horde: travel from Orgrimmar after starting the quest chain