The rock of Kalymnos is top-quality limestone. It is a little sharp in places, but free of choss (aka rotten, loose rock). There is nothing monotonous about climbing on Kalymnos: there is a great variety of rock, with slabs, walls with delicate moves, pumpy routes with pockets and stalactites or tufas on overhanging rock and roofs. In some respects the rock resembles that of Thailand, only a little sharper.
Many visitors have described the equipping of routes on Kalymnos as “the epitome of sport climbing.” At the moment (2014) there are 80 sport crags – mainly west and south facing – with approximately 2300 routes ranging from F4a to F9a, although there are quite a few project routes which are expected to exceed 9a. All have an athletic, steep and challenging sport climbing character and are equipped in a sensible and friendly manner using stainless steel bolts.