hide, conceal, secrete, hidden
濳 centers on being out of sight: hiding, concealing, or secreting something away. The water radical suggests submersion or covering, which fits the idea of making something hidden.
濳 is a variant form of 潜. Both combine 氵 (water) with a phonetic component that also carries the idea of hiding or going under. The exact historical development of the 㬱 component is uncertain.
Water 氵 covers and hides things. The right side 㬱 looks like a complex hidden object being submerged. Together, 濳 means to hide or conceal under water.
For セン, imagine a secret hidden underwater cave that only a few can sense: sense -> セン, and the hidden cave stays concealed.