The phrase "come ashore" usually refers to the act of leaving water and reaching land. Its antonyms can vary depending on the context, but some may include "set sail," "embark," or "launch" if you would like to stay on the water or depart from the shore. Other antonyms can include "retreat," "withdraw," or "recede" if you would like to move away from the shore or return to water. Alternatively, if you would like to stay on the shore, your antonyms could be "stay put," "remain," or "linger." Overall, the antonyms for "come ashore" depend on the speaker's intended action and direction.