HMCS Thunder (hull number MCB 161) was a Bay-class minesweeper that served in the Royal Canadian Navy during the Cold War.

The Bay class were designed and ordered as replacements for the Second World War-era minesweepers that the Royal Canadian Navy operated at the time.

[2][note 1] The Bay-class minesweepers were powered by two GM 12-cylinder diesel engines driving two shafts creating 2,400 brake horsepower (1,800 kW).

[3][4] The ships were armed with one 40 mm Bofors gun and were equipped with minesweeping gear.

[5][6] The vessel was commissioned into the Royal Canadian Navy on 3 October 1957 with the hull identification number 161.