In what can best be described as the most adorable invasion ever, hundreds of manatees recently took over a wildlife refuge in Florida, prompting the place to shut down.

For all of Monday and part of Tuesday, Three Sisters Springs - a complex of warm-water springs in Crystal River, Fla. - closed their doors when more than 300 manatees flooded in, Tampa Bay's WTSP-TV reported.

The park is a natural refuge for these gentle giants. Many manatees periodically move into the springs during cold weather events, where they rest and recharge in the warm waters. But when the number hit 300, the US Fish and Wildlife Service (FWS) asked the park to close for the manatees' protection.

Though this type of shutdown may seem unusual it isn't unheard of.

"Because manatees don't have any blubber to help them stay warm, they have to come into these warm water springs to stay warm. If not, they could get cold-stress and die," Kimberly Sykes, assistant manager of the Crystal River National Wildlife Refuge, told Business Insider.

These animals rarely venture into waters below 68 degrees Fahrenheit (20 Celsius).

And while the recent manatee rush is a sight to be seen, this isn't even the largest number of manatees to visit the springs before.

"We've recorded over 580 in the springs at one time," Sykes said.

Manatees are protected under the Endangered Species Act, and keeping their habitat safe is a priority for Florida wildlife managers. The Crystal River National Wildlife Refuge accommodates hundreds of park visitors at a time. Just recently, on Dec. 27, was one of the busiest days of the year, with 842 swimmers and 340 boaters at the springs. And with some much activity around, FWS officials decided it would be safest for the manatees if the park closed down and the animals got their needed rest.

According to a news release from the Florida Fish and Wildlife Conservation Commission (FWC), the gentle, slow-moving nature of Florida manatees make them vulnerable to deadly run-ins with boaters. Their wrinkly grayish brown skin creates a camouflage that makes these animals difficult to spot until it's too late.

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