The wooden walkways are the main way of moving through the lake part of the park: there are about eighteen kilometres of them in all, running over the water, along the edges of the barriers and through the shallow parts of the lakes. They are built of timber from the surrounding forests and renewed regularly, since damp and tufa wear them quickly; tufa also settles on the boards, so parts of the walkway grow into the ground over time. On most stretches the walkways have no railings, which is deliberate, as railings would block the view and speed up decay. Stepping off them is forbidden, to protect the tufa barriers. The wood is wet and slippery, and in season one walks in a single direction, following the markings.