Wetland can be defined as areas of marsh, fen, peatland or water , whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres.

Wetland is important since it is a habitat for various flora and fauna, its role in stabilizing the ecosystem by protecting the disaster, water catchment area, controlling the flood, and carbon sink.

Several example of wetlands include Kota Kinabalu Wetland: Ramsar Site, Taman Negara Johor Tanjung Piai, Taman Negara Johor Pulau Kukup,