दलदल (swamp) ऐसी आर्द्रभूमि होती है जिसमें वृक्ष, क्षुप और अन्य काष्ठीय पौधे उग रहे हों। ऐसा दलदली क्षेत्र जिसमें घास या अन्य छोटे पौधे ही उग रहें हो कच्छभूमि (marsh) कहलाता है। दलदली क्षेत्रों में अक्सर वन उग रहे होते हैं।

A swamp is a forested wetland. Swamps are considered to be transition zones because both land and water play a role in creating this environment. Swamps vary in size and are located all around the world. The water of a swamp may be fresh water, brackish water, or seawater. Freshwater swamps form along large rivers or lakes where they are critically dependent upon rainwater and seasonal flooding to maintain natural water level fluctuations. Saltwater swamps are found along tropical and subtropical coastlines. Some swamps have hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodic inundation or soil saturation. The two main types of swamp are "true" or swamp forests and "transitional" or shrub swamps. In the boreal regions of Canada, the word swamp is colloquially used for what is more formally termed a bog, fen, or muskeg. Some of the world's largest swamps are found along major rivers such as the Amazon, the Mississippi, and the Congo.