Chapter 6 addresses the protection of the marine environment. The seas are common pool resources that have become open access resources owing to the pollution that states discharge into the seas. This chapter examines the different regulatory approaches that have been adopted by states to change the open access character of the seas and oceans, such as the Law of the Sea Convention, the MARPOL Convention, the London Dumping Convention, and various regional conventions including those on the Mediterranean Sea, the Caribbean Sea, and the North-East Atlantic. The chapter concludes that, despite the global regulatory efforts, the seas have remained an open access resource due to the lack of controls on pollution inputs.