'ST' (iii) was the designation of Allied convoys (together with a numerical suffix) plying the route from Sydney to Townsville, Australia, and as such reciprocals of the 'TS' (ii) series (January/May 1943).

This first convoy of this 'Sydney to Townsville' convoy series was TS.11 of 4/7 January 1943 with the 7,710-ton British Canberra, 4,608-ton Dutch Cremer, British Merkur, 4,992-ton Dutch Tasman and 7,176-ton US Willis van Deventer, escorted by the Australian minesweeper Geelong. The last was TS.34 of 24/28 May 1943 with the 4,608-ton Dutch Cremer, 7,176-ton US Ewing Young and 2,257-ton British Yarra escorted by the Australian sloop Warrego.