The terrain can vary very quickly along forest trails, where there may be muddy or boggy patches, rocky stretches, or sections running along wooden duckboards.
Most of Finland is not very hilly, but routes may include fairly steep climbs and descents - although the toughest stretches are usually only very brief, as it does not take long to reach highspots with fine views over the treetops. Steps along steeper parts of popular trails help walkers, and also protect the soil.
Most short nature trails and popular trails in national parks can be walked in fairly light footwear such as sports shoes or walking shoes, or even sports sandals during the summer. But during and after rainy weather many stretches become muddy, so rubber boots or hiking boots are often necessary - especially if you wander off paths. Strong hiking boots are preferable on rockier routes.
In the winter it's vital to wear solid footwear and more than one pair of thick socks to keep your feet warm.
In more remote parts of Lapland trekkers may have to be prepared to get their feet wet - and cold - where routes cross rivers that have to be forded.