Compass

The Compass is a new accessory item from 1.1 update. After equipping the Compass, it will display your position to the East or West of the Spawn Point in 1 foot incraments. It is used at a Tinkerer's Workshop with a Depth Meter and a Gold Watch to craft a GPS. It can be found (with varying abilities) in the Underworld After you defeat the Wall of Flesh, then a Mimic chest (an enemy that appears as a Shadow Chest until approached).