The Pier 3 is an upgrade of the Pierstorage building. It is 4x4 and stores 2500 Goods. This upgrade looks identical to the previous one. However, this version has an 10x2 dock, and thus allows more Boats.
At this level, the Super Freighter is unlocked and is able to be placed on the pier.
An update on July 10, 2012 made it possible to store piers.