Marine biology is the scientific study of marine life, organisms inhabiting the sea, uniquely classifying species by their environment rather than traditional taxonomy. This field investigates a vast and largely unknown proportion of Earth's biodiversity, found in diverse habitats from surface water layers to oceanic trenches over 10,000 meters deep, and includes organisms ranging from microscopic plankton to immense whales reaching up to 32 meters. Marine life is crucial for our planet, contributing significantly to the oxygen cycle, regulating Earth's climate, shaping shorelines, and providing invaluable resources like food, medicine, and raw materials for humans. While marine biology examines life from a "top-down" perspective, biological oceanography takes a "bottom-up" approach, focusing on how microorganisms interact with and are affected by the ocean's physics and chemistry, underscoring how much of the deep ocean still remains unexplored.