If anyone's 'looking on' just about to run Ethernet to an outbuilding/shed here's a tip:-
Having run a lot of delicate cables in my time (mainly Audio related - imagine Cat5 divide by about 10!) in most unsuitable terrain I'd very strongly suggest using standard mains water pipe (the MDPE stuff that's either blue or black - my preference is black as it doesn't 'hit you in the face' visually!), it's virtually crushproof (even when buried at a considerable depth), very difficult to damage with strimmer/hedgecutter etc, is easy to work with and form bends in, comes in a range of sizes for differing quantities of cables, is totally waterproof, comes in mega long lengths so no need for joins that are a PITA when running in the cable(s) and is mega cheap (approx £0.75 per metre)!!!
So my thoughts on the subject - feel free to ignore!!!!
Regards
z1ts