People are saying make sure that you bring rope ( 10mm builders blue polyproperlene will do) and any old rock climbing carabiners ( as many as possible ). Try to
get 50+ metres of rope. - old climbers rope is also great.

And bring waterproof walking boots and 1 litr water bottles.

I'm not going to say why you should bring it here on this open list, but just have a little think - they could well be the most useful things that you take to the whole event. Trust me on this one please - it's been VERY useful in the past...