Bubble balloons. These would be awesome decoration for an underwater themed childs party (Or maybe for something more sophisticated, too!)
use blue cellophane to cover windows and add underwater creatures to feel "under the sea"
shark photo prop. ocean themed party
Want to add some punch to your Under the Sea party? Paper streamer seaweed! overworkedsupermom.com
Jelly fish lanterns, these lanterns cost 2-5$ depending on the sizes but light up and would add to the atmosphere of the room
Mermaid theme party- love the seaweed streamers!
Blue Lemonade perfect for a Underwater Party!
Pool Noodle Coral - super easy VBS Vacation Bible School underwater ocean theme decoration idea! #mermaid #diy
Underwater Jello Treats - Fun recipe idea to make with kids!