When someone is in deep trouble, it means they're in a serious problem or difficulty. However, there are several synonyms to describe this situation. For instance, you may say they are in dire straits, in a tight spot, or in hot water. Other synonyms include in a pickle, in a bind, in a fix, in a jam, in trouble with the law, up the creek without a paddle, or in dire need of help. These phrases imply that the individual is facing a severe consequence or is in an absolute emergency. It's essential to choose the right word according to the situation as each one carries a different level of severity.