When you need a word that's deeper than "deep," consider profound.
Profundus meant literally "deep" in Latin, and profound had the same meaning when it entered English in the 14th century. But even then, it also meant "figuratively deep" — that is, very great or intense: "The new laws have had a profound impact." Of people, it means "very knowledgeable or insightful," but sometimes if a person tries to sound profound they're really just giving you superficial knowledge dressed up with big words.