The expression "like walking on air" describes a feeling of elation or extreme happiness. There are several other synonyms that can be used to describe this same feeling. For example, the phrase "over the moon" captures the same sense of happiness and joy. Additionally, the words "elated," "ecstatic," and "radiant" also accurately convey the feeling of walking on air. Another phrase that could be used is "floating on cloud nine," which captures the idea of being suspended in a state of pure bliss. Regardless of the term used, the feeling of being light and carefree is universal when experiencing extreme happiness.