'HS' was the designation of Allied convoys (together with a numerical and sometimes a literal suffix) plying the route from Halifax, Nova Scotia, to Sydney, New Brunswick, and as reciprocals of the 'SH' series (May 1942/May 1945).

The first of these 225 'Halifax to Sydney' convoys was HS.1 of 16/18 May 1942 with the 1,557-ton Norwegian Borgholm, 1,564-ton Icelandic Dettifoss, 5,080-ton British Hartbridge, 4,671-ton Norwegian Henrik Ibsen and 2,052-ton British Royalite, but no escorts. The last was HS.227 of 21/23 May 1945 with the 2,728-ton Greek Anna T, 1,870-ton British Evelyn B, 2,060-ton British Iocolite, 2,729-ton Panamanian Makena, 2,404-ton British Millican Park and 2,895-ton British Mulgrave Park, but no escorts.