Directional Freezing is a simple method to make crystal clear ice by controlling the direction that water freezes. It mainly consists of allowing water to freeze into ice from only one direction (one side of a container) and the ice will be clear until the very last part to freeze, where impurities and air bubbles are pushed towards. This is because ice forms in a lattice of water molecules, and the impurities will be pushed into regions where the water is still liquid. Directional freezing allows these impurities to be pushed into the end region of the ice. The last part to freeze (if allowed to freeze at all) will be cloudy.