We're taught something called diphthongs and hiatus. Basically they happen when two vowels are next to each other. A diphthong is a single syllable, and a hiatus is two syllables.
There are rules for which is which. In this case the vowels are A and O so it is a hiatus.
"Strč prst skrz krk."
Wiki: "Why the river is called the Canadian is unclear."