The ocean covers more than 70 percent of the surface of the planet. It holds 320 million cubic miles of water. The deepest parts of the ocean may have little or no plant life.
There are two general types of plants found in the ocean, those having roots that are attached to the ocean bottom and those not having roots which simply drift about with the water. The rooted plants in the ocean are only found in shallow water because there is not enough sunlight to sustain photosynthesis in deeper waters. Since sunlight does not penetrate more than a few hundred feet into the ocean, most of the ocean is not capable of supporting rooted plants. Nevertheless, plants are found throughout most of the oceanic surface waters.