You can buy premium quality Sonar Sea Master 3 mm Dive Cord by the metre from The Scuba Doctor.
This cord is ideal for tying/attaching bits of scuba gear together when you prefer not to use plastic zip fasteners. For example, trying bolt snaps to your dive gear.
Bolt snaps are used in a variety of ways with technical diving equipment configurations. With a few exceptions, the proper way to attach the snap to an object is to tie it on with braided nylon/polyester line. This is because nylon/polyester line is tough enough to withstand a great deal of abuse, yet can be easily cut in an emergency if the clip is jammed or entangled. While it may be easier to attach a snap with a cable tie, a simple twist is all that's necessary to break a cable tie. When you can't afford to lose an item, you should tie its snap on with nylon/polyester line.
Also good as replacement line for some dive reels.
Material: 3 mm braided polyester
Strength: 86 kg breaking strain