Ramsar sites are classified to meet the UK's commitments under the Ramsar Convention. The UK's ratification also extends to its Overseas Territories and Crown Dependencies. These sites comprise of globally important wetland areas and may extend into the marine environment.
https://www.nature.scot/professional-advice/protected-areas-and-species/protected-areas/international-designations/ramsar-sites
https://www.ramsar.org/