Image Odyssey: Jellyfish Ornaments
I’ve never done a theme tree because I tend to decorate with the handmade ornaments I’ve made every year since nursery school, but a “sea” tree could probably look spectacular.
There are a ton of excellent jellyfish ornaments out there (something about the delicate tentacles really lends itself to gorgeous craftsmanship).
They range from incredibly intricate handmade creations to less complex mass produced versions, and use a variety of materials (glass, shells, plastic, crochet, beads…) but they’re all rather charming in their own right.
(Apologies for not citing each image source, but hand pain does not allow. Three cheers for Google image reverse search!)