I found three chossy moss filled walls between 40 and 90 ft long that I traverse back and forth. They have a mixture of slab, bulges, jugs, and holds that often break off. The walls probably do little to improve my pure ice ability, but they build the forearms and calves and give me something to do when it's rainy outside. As an added bonus, since I'm only a few feet off the ground I'll place a beer at either end or on a shelf in the middle, can't restart or move on until you have a few sips.