The images that you will see do not belong to an aquarium, or to a pool. The water we see is transparent like glass, and also relatively warm by being fed by a spring. What you will see is the Crystal River, located in Florida, USA.
Thanks to its temperate waters in winter, it attracts a number of manatees, or sea cows calls. These gentle herbivores are living in shallow waters in coastal areas from the sea or river and they find this place a paradise for shelter in the cold.
Manatees get deep into the warm waters of Crystal River in winter season and remain quietly feeding until they return to the sea coast in the summer. There are some agencies that offer the possibility of diving among manatees in what today is a natural refuge, an area of Florida that encompasses several islands in the area of Kings Bay.
The Crystal River area, is indeed a paradise for wildlife both in water and on the banks.