Ōkārito Lagoon is a coastal lagoon on the West Coast of New Zealand's South Island. It is located south of Hokitika, and covers an area of about , making it the largest unmodified coastal wetland in New Zealand. It preserves a sequence of vegetation types from mature rimu forest through mānuka scrub to brackish water that has been lost in much of the rest of the West Coast. The settlement of Ōkārito is at the southern end of the lagoon. Name The lagoon's name is from the Māori , place of, and , the young shoots of the bulrush or raupō (Typha orientalis), a valued food source. Another account has Ōkārito taking its name from a rangatira named Kārito, whose daughters Mapourika and Wahapako gave their names to nearby Lake Mapourika and Lake Wahapo. The lagoon's official name has been spelled with macrons over the vowels since 2010, although it is still commonly seen written as "Okarito". Geography The lagoon is in area, mostly quite shallow. It is the largest sandbar-built estuarine wetland in the West Coast region – and the largest such unmodified wetland in all New Zealand – and is roughly in the middle of a series of wetlands that extends for 40 km, between the Wanganui River in the north and the Waiho River in the south. Around the lagoon is a low moraine ridge left by a glacier 18,000 years ago as it retreated up what is now the Whataroa River. Several small waterways drain into the lagoon, and it is the outflow of Lake Mapourika and Lake Wahapo via the Ōkārito River. At the southern end of the lagoon is the small settlement of Ōkārito. The lagoon is tidal, with large stretches of mudflat being exposed at low tide, when reliable passage for canoes is only possible along a main channel. The channel forks into several streams and creeks that can be used to enter tall coastal and rainforest. Most of the lagoon is trackless and muddy and only accessible by boat. The lagoon is a dynamic system, driven by seismic activity along the main Alpine Fault. In an earthquake, the estuary floor settles and deepens, but sediment from landslides is also washed down from the mountains, forming a spit which partly blocks the lagoon off from the sea and raises the shoreline. Tides cannot penetrate as far, and a freshwater ecosystem forms, dominated by