Questions & Answers about Sunnuntaina me patikoitiin metsässä.
Why does the sentence use patikoitiin instead of patikoimme?
In standard Finnish, "we hiked" is me patikoimme. But in spoken Finnish (puhekieli), people almost always use the pronoun me followed by the passive form of the verb. Because the action happened in the past, it uses the past passive form, patikoitiin.
How exactly do we build the past passive form patikoitiin from the verb patikoida (to hike)?
Patikoida is a Type 2 verb (ending in -da/-dä). To form the past passive for Type 2 verbs, you drop the -da/-dä ending to get the stem (patikoi-) and then add -tiin. So, patikoida becomes patikoitiin.
I learned that the essive case ending -na means "as a". Why is it used in sunnuntaina?
While the essive case often translates to "as a" (like opettajana, "as a teacher"), it is also the standard way to say that something happens "on a day" or "during a time". Adding -na to sunnuntai simply makes it "on Sunday".
Why is it metsässä (in the forest) rather than metsällä?
Metsässä uses the inessive case (-ssa/-ssä) to show you are physically inside the forest. If you used the adessive case (metsällä), it actually has a special idiomatic meaning in Finnish: "hunting" (being at the forest for a hunt). Since you are just hiking, metsässä is the correct choice.