The phrase "setting afloat" generally means to launch or start something, particularly a boat or a business project. Antonyms for "setting afloat" would be words or phrases that represent the opposite action or outcome, such as "sinking," "ending," or "closing down." Other antonyms could include "cancelling," "halting," or "stopping." All of these words carry a different connotation than "setting afloat," signifying failure, termination, or giving up. While "setting afloat" is a positive action associated with advancement and progress, its antonyms convey the opposite emotions and implications.