This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
澖 combines 氵 (water) with 閑, which likely contributes the sound. The exact historical development is uncertain.
Water 氵 beside 閑 (leisure, barrier) suggests a vast, boundless expanse of water with no clear edge.
For カン, imagine a can floating on an endless sea: can -> カン, and the water stretches without boundary.