The Habbakuk was to be approximately 2,000 feet long and have a displacement of an amazing 2,000,000 tons or more, constructed in Canada from 280,000 blocks of a sawdust/water ice mixture known as Pykrete (after its inventor Geoffrey Pyke, who proposed the Habbakuk project inspired by its slow-melting properties). The ship's deep draft would have kept it out of most harbors. Inside the vessel, protected by 50-foot-thick walls, a refrigeration plant would maintain the structure against melting. The ship would have extremely limited maneuverability, but was expected to be capable of up to 10 knots using 26 electric drive motors. Its armaments would have included 40 dual-barrelled 4.5" DP turrets and numerous light AA, and it would have housed an airstrip and up to 150 twin-engined bombers or fighters.
The Habbakuk would have been virtually impossible to sink, as it would have effectively been a streamlined iceberg kept afloat by the buoyancy of its construction materials. However, it was projected to take $70 million and 8000 people working for 8 months to construct, an expenditure which the British were unwilling to make at the time on such an experimental craft. A small prototype was constructed in Lake Patricia, Alberta, measuring only 60 feet by 30 feet, but Habbakuk itself was never begun.