The word 潜入 is formed by combining two characters, each contributing a core action to create a unified, vivid concept. The first character, 潜, carries the meaning of diving, submerging, or moving covertly beneath a surface. The second, 入, means to enter or go into. When placed together, they do not simply list actions but merge into a single, fluid motion: the act of entering by submerging or slipping in secretly, like a diver entering water or an agent slipping into a secured area, perfectly blending the notions of concealed movement and penetration.