having the appearance of depth
漼 centers on the visual impression of deep, clear water: having the appearance of depth, as if one can see far down into a transparent pool.
漼 combines the water radical 氵 with the phonetic component 崔, which likely contributes the sound and may carry a sense of high or piled-up, perhaps suggesting deep piled-up water. The exact historical development is uncertain.
The water radical 氵 beside 崔 (which looks like a mountain 山 with a bird 隹 on top) suggests water so deep it rises like a mountain, giving the appearance of depth.
For サイ, imagine a deep sigh (サイ) escaping as you gaze into the profound, clear depths of the water.