Questions & Answers about Korkein vuori on myös vaarallisin.
How is the word korkein (highest) formed from korkea (high)?
To form the superlative (the "-est" form), we add the suffix -in. When adding this to an adjective ending in two vowels like korkea, the final vowel (-a) drops out. This leaves the stem korke-, to which we add -in to make korkein.
Why does vaarallinen (dangerous) change to vaarallisin instead of just adding -in to the end?
Adjectives ending in -nen have a special rule. You must first replace the -nen with -s- to get the correct stem. For vaarallinen, the stem is vaarallis-. When you add the superlative suffix -in to that stem, it becomes vaarallisin.
Why are both korkein and vaarallisin in their basic (nominative) form here?
Because the subject of the sentence, vuori (mountain), is in the basic nominative case. Adjectives must match the case of the noun they describe. Korkein modifies the noun directly, and vaarallisin describes it across the verb on (is). Both stay in the basic form to match vuori.
Is the word order strict for myös (also) in this sentence?
Yes, myös generally sits right before the word or phrase it emphasizes. Placing it right before vaarallisin is the most natural way to say "also the most dangerous" in Finnish. Putting it at the very end of the sentence would sound unnatural.