In the Silverpine Forest along the edges of the North Tide's Run, a derelict boat rests on the shore.  Out to the west of this lies what you seek; swim too far and the ocean will crush you from fatigue.  It resides on the ocean floor in a lockbox, waiting for you to claim it.$B$BYou'll be hard pressed to survive a dive to such depths without aid, so take heart; a bubbly fissure offers renewed breath to divers seeking this half of the pendant.  Use it wisely.