Learn Croatian: Mala luka je blizu onog zelenog rta. - The small port is near that green cape.

The preposition blizu (near) requires the genitive case. Since rt (cape) is a masculine noun, its genitive form is rta. The demonstrative pronoun onaj (that) and the adjective zeleni (green) must match it in gender, number, and case, becoming onog and zelenog.

Why do onog and zelenog end in -og instead of -oga?

In the masculine and neuter genitive case, the ending for adjectives and pronouns is usually -og or -oga. The final -a is optional. You will often hear native speakers drop it in everyday speech, saying onog zelenog rta instead of onoga zelenoga rta, though both are completely correct.

Could I use kraj or pokraj instead of blizu in this sentence?

Yes, but the meaning shifts slightly. Blizu means "near" or "close to" in a general sense. Kraj and pokraj usually mean "beside" or "right next to." So if the port is right alongside the cape, kraj works perfectly. If it is just in the general vicinity, blizu is better. All three prepositions require the genitive case.

The word rt has no vowels. How does that work in Croatian?