I got fed up with transparent PVC bags that show the world what you take with you when swimming (and mine still had the Tweenies on - the boys wouldn't use it anymore!). This bag comes out of less than 1/2m (or 1/2 yard) of oilcloth/PVC coated cotton.
On the inside there is a pocket for your watch and other small items, a keyring loop so your keys don't fall out and on the outside I have put a small transparent pocket for my pool membership card so I don't forget it.
Step 1: What you need
A piece of see through PVC a bit bigger than a credit card
1" (2.5cm) piece of velcro (sew-in is best for this)
6" (15cm) piece of 1" (25mm) wide twill tape
2 yards or 2m of cord (cut into 2 equal pieces)
marking pen or pencil
6 eyelets (optional)
Step 2: Cut out the pieces
From the offcuts I cut a piece 6" x 5" (15cm x 12.5cm) - this will be the inside pocket.
Cut the clear vinyl at 4" x 3" (10cm x 7.5cm)
Step 3: Prepare the sub units
Slip the keyring onto the twill tape and sew across as close to the keyring as you can.
Step 4: Sew the top edges
HINT 2: At the beginning of each seam backstitch and then stitch over your start point to prevent unravelling, backstitch over your sewing line at the end of each seam too, this helps prevent your seams pulling apart.
On the wrong side of the main piece mark a line 3" (7.5cm) from each short side. Fold the fabric over to meet this line giving a 1 1/2" (3.75cm) hem and sew down with two rows of stitching 5mm or 1/4" apart. The large channel will form the casing for your cord. If you prefer to run your cord through eyelets, turn in a small hem on each short side and place an eyelet 2.5cm or 1" in from each edge and one centrally between these two.
Step 5: Add the pockets
On the right side (outside) of the bag, on the other side to the side with the inner pocket, sew around three sides of your clear PVC, leaving the top side unsewn.
Step 6: Sew the sides
If you want your bag to have a flat bottom fold the side seam so it lies directly on top of the bottom "fold" of the bag, mark a line about 3" (7.5cm) from the point of the triangle and sew along the marked line, repeat for the other side. Trim the triangles leaving 3/8" (1cm) seam allowance