There may be natural areas of free-standing rocks, which allow nimble walkers to jump or step from one to another, improved if necessary by rocks placed to fill wide gaps. Such areas should be chosen where the rock is rough, and not colonized by slippery algae.
Stepping-stones can also be placed in stream crossings, where large rocks with flat surfaces can be laid to be stable and firm. The interval between them should allow the average person to step easily from one to another, and each stone should be wide enough to allow both feet to be placed on it at once. In an outdoor setting the line of stones should be sinuous and appear naturalistic rather than formal.