I went along to Economy Fabrics recently and bought some 2 inch elastic plus some fabrics, which I'll share here.
also some turquoise cotton knit (which is greener than the Summer Sea blue despite the photo)
and a lovely viscose knit with brown, olive and lime green on a white background. Hopefully this will co-ordinate with the olive green safari jacket should I ever finish it!
I might decide to enliven the summer sea with some nice coral.