Learn Dutch: Al is de afdaling gevaarlijk, ik ga toch skiën. - Even if the descent is dangerous, I am still going to ski.

In this specific grammar structure, al (meaning "even if" or "even though") must be followed immediately by the verb. This creates a verb-first clause. That is why we say Al is de afdaling gevaarlijk instead of putting the subject first.

Why is the second half ik ga and not ga ik? Doesn't starting with a clause usually cause inversion?

You are completely right that starting a sentence with a normal subclause usually triggers inversion (verb-subject) in the main clause. However, these al + verb-first clauses are a special exception! The main clause that follows keeps the standard subject-verb order (ik ga).

What role does toch play in this sentence?

Here, toch translates to "still" or "anyway." It is incredibly common to include toch in the main clause of these al sentences to strongly emphasize that the action is happening despite the obstacle.

Why does skiën have two dots over the e?

The two dots (called a trema) show that a new syllable starts with the e. Without them, the letters ie would make a single "ee" sound like in the word niet. Because of the trema, you know to pronounce skiën as two separate syllables: "skee-un".