Seaweeds, plants, TREES, and ALGAE are all oxygen producers. Seaweeds are a type of marine plant that grows in shallow oceans and other bodies of water. Plants are living organisms that use photosynthesis to produce energy and oxygen. TREES are large woody plants that can grow up to hundreds of feet tall and are also capable of producing oxygen. ALGAE are a type of aquatic plant that can be found in both freshwater and saltwater environments and are also capable of producing oxygen. All of these organisms are essential for the production of oxygen on Earth.