Arguably the best adventure you can have in Snowdonia. An epic route of old mining tunnels, rusty ladders, a huge iron chain and a couple of good abseils leads you around the different quarries of Llanberis.
Grooved arete is a brilliant 7 pitch climb up the side of Tryfan in Snowdonia. My partner for the day, Matt, had never climbed outdoors before (I taught him to belay as we geared up), owned no rock shoes and had two arms which were very prone to dislocation. So to make it fair, I led the route in B2s as well, which made for a much more exciting day out.