Meet the Lume Cube: a smart flash and lighting solution that lets you capture better photos and videos with your smartphone, GoPro, or DSLR camera. Each 1.5 inch cube emits 1500 lumens of light. These lights are fully waterproof to 100 feet. They have a 1/4 20 mount on the bottom.
You can sync up to 5 cubes at the same time. The Lume Cube is compatible with action cams, digital cams, and video gear. Costs under $80.