Which of the following features has been the most influential in creating the many diverse cultures and languages of oceania? water barriers, volcanose, tropical climate, tropical vegetation.

The correct answer is - water barriers.

The fact that the people in Oceania are living on islands that are very far away from one another and are very isolated by the vast spaces of water between them contributed that the people develop lots of different languages and cultures according to their environment and personal beliefs. Also they did not had any foreign influences so were able to develop freely on their own over the centuries, so every ethnicity of Oceania has its own unique features.