There are many alternative phrases that can be used in place of "rock the boat." Some synonyms include causing trouble, disturbing the status quo, stirring things up, making waves, challenging authority, agitating, and upsetting the applecart. Each of these phrases suggests a sense of disruption or discord, indicating that something is being upset or challenged in some way. They are often used in situations where someone is pushing for change or trying to bring attention to an issue that has been overlooked or ignored. Whatever the phrase used, the intent is clear - to disrupt the status quo or challenge the prevailing norms.