Ocean is pronounced OH-shən (IPA /ˈoʊʃən/). The 'c' is /ʃ/ — say 'OH-shun' in two beats.
IPA: /ˈoʊʃən/
Syllables: OH · shən
Common ESL mistake: Learners say 'oh-see-an' as three syllables or use /s/ for the 'c'.
Tip: The 'c' is /ʃ/ — say 'OH-shun' in two beats.