The phrase "happy chance" is often used to describe an unexpected and fortunate occurrence. There are several synonyms that can be used in place of this phrase, including serendipity, luck, fortuity, and providence. Serendipity is a particularly apt substitute, as it implies a happy accident or discovery that was made by chance. Luck and fortuity both connote a sense of fortune or chance, while providence suggests a higher power or divine intervention. Other possible synonyms include coincidence, happenstance, opportunity, and stroke of luck. No matter which word is used, it is clear that such occurrences can bring great joy and satisfaction to those lucky enough to experience them.