Mangroves are distinctive ecotones characterized by species of salt-tolerant trees and shrubs that thrive in intertidal zones. Yet these vibrant ecosystems suffer from a myriad of anthropogenic and natural issues. Mangroves remain critical to protect marine biodiversity, support livelihoods of coastal communities, and provide ecosystem services such as carbon sequestration, shelter for juvenile fish, and sediment and nutrient trapping. This chapter discusses the importance of mangroves as marine ecosystems in sustenance of oceans and their relevance for the blue economy of nations. Using a desk-based qualitative study, the importance of mangroves to humankind and the resulting destruction over the years due to anthropogenic activities is studied. In addition, anthropogenic and natural stressors that impact mangroves are discussed together with approaches and efforts to ensure their preservation. To emphasize the importance of mangroves in the blue economy of a nation, Sundarbans, the world’s largest single block of mangrove forests, are discussed as a case study. Our study shows the importance of mangroves, the impact of anthropogenic actions and natural stressors on their well-being, and some efforts being taken globally to preserve this ecosystem. One observes that even though the major factors for loss of mangroves are known to be land conversion, urban development, shrimp ponds creation, overharvesting, urban pollution, mining, siltation, and natural disturbances, the loss of mangroves in recent years has slowed down possibly due to their resilience to environmental changes. However, much more needs to be done to recover the original mangrove cover as these ecosystems are critical for sustenance of life on Earth and the blue economy.