A natural swimming pool (NSP) or pond is an engineered system comprising a contained swimming vessel and a constructed wetland. The constructed wetland may be integrated with or separated from the swimming vessel. Water purification and clarification is achieved entirely via the use of biological filters, hydroponically rooted aquatic plants, and the balanced ecosystem contained within the wetland, without the use of any chemicals or devices that disinfect or sterilize the pool water. For bather health and safety, the NSP optimizes the conditions found in nature’s water bodies.