The problem with frozen seaweed is the water in the plant would melt quickly, leaving you with a box full of warm seafood and water (no good). Gel packs and dry ice work for us because they are designed to be much colder and last longer than ice. The key is to maintain a constant temperature thought the shipping process. We are now redesigning our package so it both environmentally and economically efficient. Interesting concept though; seaweed would give a nice ocean feel to the package but it probably wouldn’t keep anything cold for very long.