La Coupée, the causeway which joins big and little Sark, is about 100m long. It is a high ridge 80 metres (262 ft) above the sea which is only some three metres in width. This is gradually being eroded and Little Sark will eventually become an island (a similar process is likely to have occurred with Brecqhou close to Sark’s west coast).
The causeway used to be rather precarious, and on windy days the local residents had to crawl across it or risk getting blown off a cliff. Protective railings went up in 1900, and in 1945, the isthmus was finally paved by Nazi prisoners of war.
The causeway is flanked by two bays: La Grand Grêve to the west (right as seen from Great Sark) and Convanche Bay, part of Baleine Bay, to the east. The drop to Convanche Bay is steep, but that to La Grand Grêve is more gradual and steps have been cut into the rock, leading down to what is Sark's most extensive and popular beach.