You can make this great swimmable AND walkable mermaid skirt part of your world by following this simple tutorial.
For this project you will need:
Shiny, stretchy material (it's called "swimmer/dancer fabric)
Coordinating color tulle
Sewing machine/thread and needle (not pictured)
3/8" elastic (not pictured)
Scissors (not pictured)
You can purchase all these items at JoAnn's or any local fabric store.
I made the skirt our of remnants from other projects, but it would cost roughly $30 to make and took about 30 minutes.
The length of the fabric you will need is dependent on your body measurements and width of the fabric so I can't really give any specifics on how much fabric to get. I suggest you wrap the fabric around you to see how much you need to get before purchasing.