Hawaii has a population of Scalloped Hammerhead sharks (Sphyrna lewini), forming aggregations at specific sites. Yet our lab catches them rarely, has never tagged an adult female, so we know little of this populations' ecology. To learn more, we need a completely different approach to tagging these sharks. We're proposing to use Closed-Circuit Rebreather (CCR) technology to stealthily tag four individuals from S. lewini aggregations, using a modified pole-spear to equip them with satellite tags.