A shore lead is an oceanographic

Oceanography

Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...

 term for a waterway

Waterway

A waterway is any navigable body of water. Waterways can include rivers, lakes, seas, oceans, and canals. In order for a waterway to be navigable, it must meet several criteria:...

 opening between pack ice and shore

Shore

A shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In Physical Oceanography a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore,...

. While the gap of water may be as narrow as a tide

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

 crack if closed by wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

 or currents, it can be as wide as 1000 feet (304.8 m). Its formation can be influenced by tidal action, or subsurface conditions, such as current

Ocean current

An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon this mean flow, such as breaking waves, wind, Coriolis effect, cabbeling, temperature and salinity differences and tides caused by the gravitational pull of the Moon and the Sun...

 and ocean floor. Commonly, a shore lead is navigable

Navigation

Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...

 by surface vessels.

An opening ("lead") between pack ice and fast ice

Fast ice

Fast ice is sea ice that has frozen along coasts along the shoals, or to the sea floor over shallow parts of the continental shelf, and extends out from land into sea. In Antarctica, fast ice may also extend between grounded icebergs...

is referred to as a flaw lead.