Ice is a great way to cool the smoke being produced, which creates a smooth, flavorful hit. Many downstems are built with an ice catcher at the end, which holds ice and cools the smoke before it hits the water reservoir. Some put ice directly into the water reservoir, but this can easily create water vapor, which should not be inhaled. Ice catchers for bongs is an easy way to increase the quality of your bong experience, so be on the lookout for it when bong shopping!