What is the scientific study of the phenomena of oceans, including their physical, chemical, and biological features?

Oceanography is the branch of science that specifically deals with the study of the oceans. It encompasses a wide range of topics, including the physical characteristics of ocean water, its chemical composition, and the diverse biological organisms that inhabit marine environments. This discipline seeks to understand the processes that govern ocean dynamics, the interactions between the ocean and the atmosphere, and the impact of human activities on marine ecosystems.

In contrast, geohydrology focuses on the distribution and movement of groundwater, cosmology studies the universe's origin and structure, and hydrogeology combines aspects of geology and hydrology to understand how water interacts with geological formations. None of these fields specifically address all phenomena related to the oceans as comprehensively as oceanography does, making it the correct answer.