The establishment of marine protected areas, also known as MPAs, aims to conserve marine ecosystems as close to their natural state as possible. In principle, the aim is to protect or restore biodiversity, i.e. the diversity of species, habitats, and ecosystem functions. This goal is pursued through conservation measures to minimise the negative impact of human activities and, where possible, climate change. A very important concern is to prevent overfishing of commercially exploited fish, squid, crabs, or even mussels, or to offer already overfished stocks protected areas for recovery.

MPAs today come in a wide variety of forms, in terms of protection status and size. In the rarest cases, all human activities are prohibited (so-called no-take MPAs). However, most often these no-take zones are part of larger multiple-use MPAs where human activities are restricted and managed but are not completely excluded.  MPAs can also vary greatly in size. Many coastal MPAs are relatively small and fall within national jurisdiction, such as a local estuary. However, there are also examples of larger MPAs covering entire biogeographic regions over 1000s of km² in international waters.  When designed well, using scientific evidence, adequately implemented and enforced MPAs (especially no-take MPAs) have been shown to be useful tools for marine conservation and even increase fishery yields and profits.

More than 70 nations from around the globe have so far signed up to the 30x30 initiative under the Global Ocean Alliance (GOA) that aims to protect 30% of the global ocean via protected areas by the year 2030. This goal has recently been formally included in the Biodiversity Treaty of the Convention on Biological Diversity (CBD).

Under the Antarctic Treaty, the waters around Antarctica are international waters and do not belong to any one nation. They should only be used and explored peacefully and sustainably. The use and protection of Antarctic marine living resources is governed under the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR). Established in 1982, CCAMLR currently has 28 member states that meet regularly to discuss how to manage Antarctica’s ecosystems sustainably.

CCAMLR made a commitment in 2009 to create a representative network of MPAs around Antarctica. To this end, The CCAMLR Convention Area was divided into nine MPA planning domains, ensuring that the system of MPAs developed around Antarctica is representative and comprehensive. The process and requirements for the establishment of CCAMLR MPAs are set forth in Conservation Measure 91-04.

To date, CCAMLR has successfully adopted two MPAs (one in the South Orkney Islands and one in the Ross Sea). For more information on existing and proposed CCAMLR MPAs, see the CCAMLR MPA Information Repository (CMIR).

MPA proposals may be brought forward by one or more CCAMLR Member States. Proposals must be based on the "best available science", be specific in the geographic area covered, include objectives to be achieved, as well as the activities to be restricted or prohibited. The proposal must then be unanimously approved by all CCAMLR members. Once passed, the MPA must also set out a research and monitoring plan.