Zoom in on this satellite image of South Korea’s southern coast and you’ll notice the grid-like patterns in the water are made up of hundreds of little rectangles. These are seaweed fields, held by ropes and buoys that keep them close to the surface during high tide and off the seafloor during low tide.
Photo Credit: NASA Earth Observatory image by Jesse Allen, using Landsat data from the U.S. Geological Survey
Below is a close-crop of the image up top. Writing for NASA Earth Observatory, Adam Voiland provides more details on what it is we’re seeing:

Since 1970, farmed seaweed production has increased by approximately 8 percent per year. Today, about 90 percent of all the seaweed that humans consume globally is farmed. That may be good for the environment. In comparison to other types of food production, seaweed farming has a light environmental footprint because it does not require fresh water or fertilizer.
Below you’ll find the full, zoomable image of the region, courtesy of NASA Earth Observatory. If you’re up for a little exploring, you can spot these seaweed fields on Google Maps, as well.
View original article at: South Korean Seaweed Farms, From Space