Project Habakkuk: The Unsinkable Aircraft Carrier Made of Ice

British inventor Geoffrey Pyke proposed building an aircraft carrier from 'Pykrete' — a mixture of 86% sawdust and 14% water frozen together. Pykrete was as strong as concrete but would float. The ship, called Habakkuk, would have been 2,000 feet long and been able to be repaired by simply spraying seawater on damaged areas. A 60-foot prototype was built at Patricia Lake in Alberta, Canada. It required massive refrigeration and the cost projections were enormous. The project was cancelled after it became clear that even a full-scale ship would need more refrigeration equipment than any shipyard could supply.