The phrase "immersed in" is commonly used to indicate a sense of complete absorption or involvement in a particular activity or situation. There are many synonyms that can be used to replace this phrase and still convey the same meaning. Some common options include "engrossed in," "absorbed in," "enveloped in," "lost in," "wrapped up in," and "consumed by." Each of these phrases suggests a deep level of involvement or preoccupation, and they can be substituted for "immersed in" depending on the context and tone of the surrounding text.