Swartvlei is a large estuarine lake system forming a vital part of the Garden Route's coastal wetlands. It is one of the few warm temperate coastal lake systems in southern Africa, fringed by coastal fynbos and evergreen forests. The system uniquely connects to the marine environment, comprising a lagoon and flood plain linked by a natural channel called the Serpentine to other lakes, with Swartvlei itself being the largest lake in the district. The estuary mouth is a dynamic feature, often classified as a "blind estuary," where a sandbar regularly forms, blocking the direct connection to the Indian Ocean. This cyclical opening and closing is a natural process crucial for the life cycle of many fish species. The lake is separated from the ocean by a narrow dune strip, and the estuary area provides safe bathing. The entire system is recognized for its ecological value under the Ramsar Convention on Wetlands.