The Kraken
From WoWWiki
The Kraken (formerly Sword of Wrynn) is the main sea-going transport that runs between Stormwind Harbor and the port of Valiance Keep, in the Borean Tundra of western Northrend. Unlike other intercontinental sea-based transport, the Kraken is a steam-powered icebreaker, ideal for traversing the frozen seas of Northrend.
