The word "submerged in" can be replaced with various other words depending on the context. For instance, if we talk about being fully engrossed in something, we can use the word "absorbed in" instead of submerged in. Similarly, if we want to convey the meaning of being drowned in thoughts or emotions, we can use the phrase "immersed in." "Sunk in" can also be used to describe the state of being mentally or emotionally involved in something. Other synonyms for submerged can include "completely consumed in," "obsessed with," "lost in," "overwhelmed by," and "swallowed up in." The choice of alternate words depends on the particular meaning or emphasis that one wants to convey in their statement.