A geminate root, doubling its last letter, and carrying three strands that all share the idea of depth and clarity in a medium. One is diving, sinking down into water (לִצְלֹל). One is shadow, what falls when light is blocked (צֵל). One is sound, a clear tone travelling through air (צְלִיל). Down into water, across the ground as shade, out through air as a tone: the same root tracks something moving through a medium. Every word below is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
Being a geminate root (the ל is doubled), the verbs contract: לִצְלֹל keeps both ל letters, while the hif'il לְהָצֵל collapses them. The pa'al carries diving / going deep; the hif'il carries shading. The sound strand (צְלִיל) lives in the nouns, not in a verb here.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.