Impressive drone footage captures hundreds of manatees gathered in warm water springs in Florida. The video was shared by the Citrus County government and shows the marine mammals gathered at Three Sisters Springs in the Crystal River National Wildlife Refuge. Manatees often seek springs to stay warm, as other waters can become cold over the winter months. They need to be in water that is no colder than 68F (20C) to maintain a safe internal body temperature. If the marine mammals are in water that is any colder for an extended period, they may get “cold stress” which makes them vulnerable to disease and death.