Three Mile Lagoon is a coastal lagoon located south of Ōkārito on the West Coast of New Zealand's South Island. It is part of the Westland Tai Poutini National Park. The lagoon is accessible via the Three Mile Pack Track, a historic coastal walking trail that leads from Ōkārito. This track passes through native forest and wetlands, including stands of rimu, rata, and silver pine, before reaching the lagoon after approximately a three-hour return walk. The lagoon itself is separated from the Tasman Sea by a beach, and the area is known for its coastal wetland environment. Paddling access is likely via this beach, which can be walked at low to middling tide, suggesting that launch and retrieval are tide-dependent. The surrounding area is remote and offers a sense of isolation, with the lagoon being a notable feature on a scenic coastal hike. The environment supports native birdlife, including species such as white herons and black swans. The lagoon's status within the national park implies general conservation regulations apply, and it is identified as a Marine Protected Area.