Vivonne Bay hat
Named after one of the most beautiful beaches. Vivonne Bay on Kangaroo Island, off the coast of South Australia. I knit my versions (both medium sized) in Cascade 220 and Noro Cash Iroha. Due to its drape the Noro is a little baggier. You could lighten it up further with a cotton yarn in a similar gauge, or go snuggly with a warmer wool like Malabrigo Worsted.
The medium uses approximately 86 yards 78.5m yarn. The pattern (from Barbara Walker’s 1st Treasury) is a 6 stitch repeat, so you could easily size it down further for a child by casting on a lower multiple of 6 and working less repeats.
ETA: many users have suggested making the ribbing longer - you might like to try with up to 2-2.5 inches of ribbing, I think this does look a lot better.