IPA: /səbˈmɜːrst/
KK: /səbˈmɜrst/
Describing something that is covered or located beneath the surface of water.
The submersed plants provide shelter for fish in the lake.
Submersed is formed from "sub-" (meaning under) and "mergere" (meaning to plunge or immerse). The word describes something that has been plunged or immersed under a surface, typically water.
Think of something being 'under' ('sub-') the water as it is 'plunged' ('mergere') — that's why submersed means to be under the surface.