The Epilimnion 1, digital photography manipulation, 11.5 x 17.5in (29.2 x 44.45cm), 18 x 24in (framed), $300.00 In a small body of water such as a pond, the topmost layer of water is called the epilimnion. It is the warmest and most oxygenated layer and is therefore home to the majority of plants and animals.