Largest icebreaker ever

Who: SS Manhattan
When: 1969

The largest converted icebreaker was the 306.9 m (1,007 ft) long SS Manhattan which was converted into a 152,407 tonne (335 million lb) icebreaker by the Humble Oil Co. Fitted with protective steel armour 2.7 m (9 ft) thick, 9.1 m (30 ft) deep and 204 m (670 ft) long, Manhattan made a double voyage through the North-West Passage in arctic Canada from 24 August to 12 November 1969.