I had the idea for at least a year of making a mermaid sleep sack, but all the patterns I liked were crochet! Finally, one day I realized that I was going to have to make a pattern myself--so I did!

Edit: This pattern was originally created with Cascade 220 Superwash (photo #1), but I found that it actually looked much better in Encore Worsted (photo #2). If using Encore, note that the gauge is actually 4 sts x 6 rows = 1 inch.