Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Wave waves big small green water lake sea ocean river bay underwater drone aerial overhead moss seaweed alga lichen hydrophyte swamp quicksand marsh bog quagmire subaqua submerged brown muddy turbid still water ecosystem habitat nature natural. 4K UHD 3840×2160.