S1·E53 The Water Nymph

One day, in the aftermath of the gold fever, Sniff walks off upstream to look for gold in the river-bed. He gets lost in a thick mist, and suddenly comes upon a small pond, created by a pile of driftwood. What he sees there makes him completely spell-bound and he walks home in a trance. Learning about this Moomin tails Sniff when he goes back next day - and finds himself spell-bound in just the same way. This happens to most men in Moominvalley, until the women decide they have to do something about it - but before they can act Nature decides to take a hand.