The San Francisco Bay can be viewed as a geographic paradox: a place and a void. The collective Bay (composed of San Francisco Bay, San Pablo Bay, and Suisun Bay) both unites and divides the community of the Bay Area, giving identity to the region while separating its populace. The Bay is a backspace, where hardened surfaces of the industrial city crumble into the water—as well as a shorefront, with designed parks and recreational marinas. It is intensely visited in some areas and nearly inaccessible in others; its beauty is acclaimed, its dumping grounds unparalleled. Its sparkling water is refreshed from Sierra snowmelt, its sewer outfalls and urban runoff robust. Once intensely militarized, it is now, just as intensely, demilitarized. In a sense, the Bay is a natural entity, borne of great rivers draining the entire Central Valley of California, however, every inch of its shoreline today is the product of human activity, by either intent or incident.