After reading some of the dangers people have come accross the last few weeks, I'm thinking it would be a good idea to get some kind of cutting device for lines. Hopefully it will never be used but peace of mind is a wonderful thing.

Ideally some kind of weather proof / water proof retractable line cutter than can attach to your harness would be ideal.

Does this sort of thing exist?

Heaps of harnesses come with them buuilt in. I just bought a mystic which comes with a hook knife. You should be able to buy one after market.

How are people attaching these so that they are accesible with one hand / underwater / being dragged / etc?

PS Don't forget to add about $10 to the prices for postage.

If you dont wanna trust your life to a piece of plastic or carbon and a razor blade and want to invest in something lifesaving.

Consider the PR2 tactical rescue knife. This is a Chromium Molybdenum Vanadium (CrMoV) Single forged blade. Its very high wearing, very strong and has incredible tensile and torsional strength (wont bend or break, nor dull with use). It has a slot carved into the tang with a gap of about .750cm to allow for a line to slip into without having to open the knife (the same idea as a hook knife). The good thing about this knife is that it will cut anything. Nylon lines, Dyneema lines, Carbon fibres, it has even been documented to cut hydraulic flight lines. The knife comes with a lifetime warranty is used solely by the Australian SAS and has a centrepunch made of hardened ceramic used for smashing car windows (for rescue purposes).

I have one and have used it many times, none in survival situations luckily.

If you live in WA you can purchase them from a Military Outfitting store called "the Kit Bag" in Midvale. They cost around $200 and are well worth it. They are also made with teflon edging and are very waterproof.