Due to human activities exerting more pressure on the ocean environment, it poses a significant danger to the long-term survival of marine species and ecosystems, resulting in a decline in marine biodiversity. The world's marine ecosystems face numerous significant threats that jeopardize their health and stability. Among these threats, climate change, overfishing, and pollution emerge as primary concerns. Climate change contributes to rising sea temperatures, ocean acidification, and sea-level rise, leading to detrimental impacts on marine habitats and biodiversity. Overfishing disrupts the delicate balance of marine food chains, depleting fish stocks and undermining the overall health of aquatic ecosystems. Pollution, specifically plastic pollution, carbon pollution, and oil spills, further exacerbate the degradation of marine environments, causing harm to marine organisms and their habitats. This article provides an overview of these major threats and highlights the urgent need for collective action to conserve and protect our marine ecosystems for future generations.