Literal:
* The treasure chest was submerged beneath the murky waters of the lagoon.
* After the heavy rains, the entire neighborhood was submerged in floodwaters.
* The submarine submerged to a depth of 1,000 feet.
Figurative:
* The country was submerged in a wave of political unrest.
* Her thoughts were submerged in a sea of doubt.
* He was submerged in work and had no time for anything else.
You can use "submerged" to describe something that is completely covered by water or another fluid, or to describe something that is overwhelmed or consumed by something else, like emotions or work.