A ﬂaw lead is a navigable passage between ﬂoating pack and landfast ice. One side of the lead, the pack, is in more or less constant motion. The other side is motionless, a sheet of fast ice ﬁrmly attached to the shore or to an ice front, the seaward edge of an ice shelf. Fast ice may extend anywhere from a few feet to nearly two hundred miles from shore, and ﬂaw leads are often temporary, their creation always subject to shifts in the direction of the wind. (Grounded or ﬂoating icebergs sometimes develop aprons of “fast ice,” but open water at the edge of such ice constitutes one of the ﬂoating pack’s many transitory “open leads.”) When a sheet of landfast ice rises more than six and a half feet above water, it can be reclassiﬁed as an ice shelf and it creates a special type of ﬂaw lead. British explorer Robert Falcon Scott, sailing in the ﬂaw lead of Antarctica’s Ross Ice Shelf, a mass of ice the size of France, described its ice front as “a relentless coast of high ice cliffs,” much of it more than one hundred feet high (and descending, he was unaware, hundreds of feet below his ship). In the Arctic, this type of ﬂaw lead is rare. Far more common is the dynamic system of opening and closing ﬂaw leads maintained by alternating on- and offshore winds, an unpredictable situation that makes navigating in the ﬂaw leads dangerous—and frustrating.