The marine and coastal ecosystem plays an important role for the sustainable development and economic growth of a country. The coastal areas of Pakistan are spread over 990 Km. Besides this coastal area, an Exclusive Economic Zone (EEZ) has an area of about 240,000 sq km and maritime zone of Pakistan, including the continental shelf, extends up to 350 nautical miles from the coastline. This area features a wide diversity of ecological and geological characteristics and is home to distinct range of mangroves, green turtles, fishes, dolphins, whales, corals, minerals, volcanoes, ports, and harbours. The marine and coastal ecosystem of Pakistan is being threatened by various environmental challenges that are causing destruction and degradation of biodiversity of this area. First of all, climate change is one of the biggest challenges for sustainability of coastal and marine life. Climate Change is resulting into an increase in the sea level and intrusion into coastal area. Similarly, glaciers melting due to climate change are a major cause of floods in the country. The lack of water reservoirs, leads these floods towards lower riparian and finally into the sea, destroying coastal areas in its path. The sudden and increasing frequency of heatwaves in Karachi is also life threatening for flora and fauna of this area. The mangroves forests on the coastal areas cover huge ground. According to Pakistan National Strategy and Action Plan, eight species of mangroves have been reported, though only four are surviving at present. These mangroves forests are also the habitat of wildlife that is also endangered due to vanishing mangroves that are under threats due to many reasons that include diversion of fresh waters, overexploitation by local communities for commercial purposes and salinity issues. Another important reason for marine and ecosystem challenges in Pakistan is use of non-sustainable land on the coastal areas. Karachi, being the main seaport of Pakistan is the hub of economic and commercial activities. Moreover, a large number of tourists visit the beach of Karachi to enjoy but do not comply with environmental protection measures. The unsustainable pattern of activities like continuous mineral extractions and fishing in the Exclusive Economic Zone also undermines the environment and biodiversity of marine and coastal areas The presence of Navy bases and their military exercises in the sea is another challenge. However, the navy is also playing an important role in the protection of mangroves forests of this area. All these activities are also a big challenge for the sustainability of natural biodiversity on the coastal areas. The unsustainable pattern of activities like continuous minerals extractions and fishing in the Exclusive Economic Zone also undermines the environment and biodiversity of marine and coastal areas. Another major issue is the discharge of hazardous waste into the sea. This waste includes hospital wastages, plastic pollution, and oil spills from ships. A study by WWF indicates that 65 per cent of litter on coastal area consists plastic bottles, wrappers, bags, disposable utensils etc. Pakistan has a world-leading ship breaking industry in Gaddani. This ship industry is the biggest source of discharging heavy metal pollutants into the sea. Karachi has copious industrial zones but lacks proper waste management system ultimately finding destination into the sea. The fish and other marine life swallow these tiny particles of metals, plastic, and poisonous substances that become fatal to their survival. Pakistan has signed many international conventions and treaties to protect environment and biodiversity. Under these obligations, Pakistan has committed to protecting its marine and coastal biodiversity. Some of these are Paris Agreement, Convention on Biological Diversity (CBD), Convention on Trade of Endangered Species (CITES), RAMSAR Convention, Kyoto Protocol, United Nation Convention on Law of Sea, Basal Convention, Stockholm Convention. Pakistan took many initiatives in the past to protect marine coastal ecosystems. These steps involved the establishment of the Marine Pollution Control Board in 1994, National Institute of Oceanology in 1981 and formulation of Pakistan National Strategy and Action Plan. Above all, recently Pakistan declared Astola and Churna Island as the first protected marine areas of the country. All these efforts are appreciable but are not enough to overcome all the challenges. Still, environment and biodiversity of marine and coastal areas are confronted with many unnoticed threats that require due and timely attention from the government, the private sector and common people. The writer is based in Islamabad and works on environmental issues. She can be reached at zilehuma_1@hotmail.com, and tweets at @zilehumma_1 Published in Daily Times, July 9th 2018.