The Epilimnion 2, digital photography manipulation, 10 x 7.5in, (25.4 x 19.05cm), 25 x 19in (framed), $300.00 In a small body of water such as a pond, the topmost layer of water is called the epilemnion. It is the warmest and most oxygenated layer and is therefore home to the majority of plants and animals.