I thought waves would be appropriate, but am worrying that I may not be able to sew curves together without any puckering. If I have a hesitation over any part of a project, everything comes to a standstill until I wait for a better idea to come along. I tired of waiting after ten months and started tackling large pieces of previously used fabric to cut them down into rectangles. These pieces had odd shapes since I had cut out smaller pieces for the top using templates. I worked with two layers of fabric at a time, pinning them together. I then divided the rectangles into three strips.
Then next step will be to sew the three strips of each fabric end to end to span the width of the quilt. I will then pin two strips of different fabrics together and cut out a wave shape. At that point, I suspect I will thoroughly consult some of my quilting books on curves, then begin sewing. Hopefully, all the strips will add up to the length of the quilt once they are sewn together in waves. If not, I'll add a sandy beach.
I'm planning on making the backing several inches wider and longer than the top, so that I can wrap the borders over from the back to the front. That way the border will have waves too.