沉潜

沉潜	chén qián	to lurk under water / to immerse oneself in (study etc) / to lie low; to keep a low profile / quiet; reserved; self-possessed
沉	chén	to submerge / to immerse / to sink / to keep down / to lower / to drop / deep / profound / heavy
潜	qián	hidden / secret / latent / to hide / to conceal / to submerge / to dive