In Finland we have this thing called "Everyman's Rights". In a nutshell, it means that nature is for everyone to access and enjoy. While these rights are not laid out in the law, certain things are specifically allowed based on our age-old customs.
It goes without saying that you aren't allowed to harm nature or cause disturbance but these are subjective matters. The range of things you can do in Finland is surprisingly wide and applies to all people, not just citizens. Without permission from the landowner, you can:
It is commonly prohibited to:
Certain limitations apply to nature reserves on a case-by-case basis.
It is only possible to retain rights by exercising them. There are people who would gladly prohibit others from doing various things, and the best antidote is tolerization: do it often enough and spread the good word.
That being said, make sure you are informed and responsible about your business. What you carry to the forest, you carry away: leave no trace behind if you can help it. If someone is annoyed by your presence that's on them.