You will need a blue A4 sheet of cardboard for the sea and some small pieces of colored paper to make the sea creatures.
Fold the blue cardboard in two. Draw 7-8 wavy lines, starting with the folded edge and stopping a little before the end.
Fold the shape and cut the lines with scissors as shown on picture 5. Open the paper and start folding the strips in and out, alternating directions. They will stand for ‘the sea’ on which the kids can then glue their fish.