Home of the deepest spot on the planet, the Mariana subduction system serves as a valuable natural laboratory for testing ideas about what governs the distribution of animals at hydrothermal vent systems. The deep trench, shallow to mid-depth volcanic arc, and mid-depth to deep spreading back-arc, provide a wide variety of habitats for research. Of these, more than 600 km of the back-arc has remained relatively unexplored. This December, the science team will follow up from a discovery cruise that occurred on Falkor last winter. During the previous visit, three new hydrothermal vents were discovered; one of them being among the deepest vents in the world. This time, the team will return with our brand-new 4,500 m capable ROV SuBastian to explore the life and activity at the vent sites.