Watch divers rescue four whale sharks—each the size of a car—trapped in fishing nets. | National Geographic

Whale sharks are filter feeders that consume enormous amounts of plankton and small fish. In doing so, they help maintain the balance of the marine food web and the ecosystem at large. We still don't know much about these gentle giants, but their significance as a keystone species makes their preservation a priority. Learn more at: https://on.natgeo.com/3Xf6vlV | National Geographic