In spoken Finnish, you will frequently hear people use forms of the pronoun mikä (such as missä, mistä, or mihin) to refer to physical places. However, strict standard written Finnish requires a different approach.
When referring back to a physical location, you must use the relative pronoun joka. Depending on whether you are stationary, leaving, or entering the location, you will use its inner local cases.
In Which / Where (jossa)
When describing an action happening inside or at a location, standard written Finnish uses the inessive form jossa instead of missä.
| This is an underground route where a crawler must be brave. | Tämä on maanalainen reitti, jossa ryömijän täytyy olla rohkea. |
| The labyrinthine cavern where we are standing is another researcher's discovery. | Sokkeloinen onkalo, jossa seisomme, on toisen tutkijan löytö. |
From Which / From Where (josta)
When the action originates or moves away from the location, use the elative form josta instead of mistä.
| The underground chamber from which we found the stone is very labyrinthine. | Maanalainen kammio, josta löysimme kiven, on hyvin sokkeloinen. |
| The wall from which the stalactite hangs is really damp. | Seinä, josta tippukivi riippuu, on todella kostea. |
To Which / To Where (jonne)
When there is movement towards or into a location, use jonne. This formally replaces mihin or minne when acting as a relative pronoun.
| The cavern where we are going must be explored with a compass. | Onkalo, jonne menemme, on tutkittava kompassilla. |
| The unexplored cliff where we can wander off looks dangerous. | Tutkimaton jyrkänne, jonne voimme harhautua, on vaarallisen näköinen. |
Pay close attention to the verb in the relative clause, as it dictates whether you need the stationary jossa, the departing josta, or the arriving jonne.