Iron is the most important micronutrient in the ocean, yet its sources and sinks to and from the ocean are poorly constrained. The GP16 Eastern Pacific Zonal Transect cruise from Peru to Tahiti in 2013 along 12-15°S crossed the large eastern tropical South Pacific oxygen deficient zone (ODZ) in the eastern half of the transect and the East Pacific Rise (EPR) hydrothermal plume in the western half. Both features were expected to be important sources of dissolved iron into the ocean interior. The EPR hydrothermal iron plume was found to extend for several thousands of kilometers around 2500 m, greatly exceeding prior expectations. In contrast, there was no significant iron plume in the heart of the ODZ around 300 m that extended beyond the coastal margin, despite the ODZ penetrating several thousand of kilometers into the interior. Surprisingly, a deep coastal iron plume in oxygenated waters centered around 2000 m was observed to penetrate >1000 km into the interior. In this talk, I’ll examine the reasons behind the unexpected high Fe from the oxygenated deep slope relative to the more reducing ODZ above.