Lake Hylia

Lake Hylia is a recurring location in the Legend of Zelda series. It is the largest body of water in Hyrule, usually fed by a river that has its source in the mountains.

The Legend of Zelda: A Link to the Past
Lake Hylia is in southeast Hyrule and has small caves coming off it. In the center of the lake is an island featuring the Fountain of Happiness, a fairy spring that is inhabited by Venus, Queen of the Fairies, who will upgrade Links ability to carry bombs or arrows if she is given enough money. Outside the pond is a warp tile that grants access to the Ice Palace in the Dark World.

The lake itself is fed from Zora's River, which in turn flows from Death Mountain.

The Legend of Zelda: Ocarina of Time
Lake Hylia is a lake in the south of Hyrule. It is closed off by a gate but can be entered on Epona or by scaling a ladder hidden behind one gate pillar. There is also a portal from Zora's Domain and it is possible to float down river from Gerudo Valley. Lake Hylia's water is provided by the ever-rushing streams of Zora's River. There are numerous small islands in the lake linked by bridges. The largest islet is the warp point for the Serenade of Water, and below it lies the Water Temple. There is a large tree atop this islet. At the shores of Lake Hylia, there is a lakeside laboratory and a fishing house.

The Legend of Zelda: Four Swords Adventures
Lake Hylia is the first stage in the Whereabouts of the Wind, and, consequently, the first stage in the game. It is filled with trees, underground caves, and waterfalls, and it serves primarily as a tutorial to the game, introducing Link to different items, combat styles, and other aspects of the game. Link begins in a large open area surrounded on three sides by forestry. Here he meets Kaepora Gaebora for the first time. Throughout the stage, Link can obtain two items:Boomerang, Blue Bracelet, and the Fire Rod. Near the end of the stage, Link must defeat a group of Hylian Knights and their leader. At the end of the stage, Link must break the four-eyed barrier with his sword, allowing him to pass on to the Cave of No Return.

The Legend of Zelda: The Minish Cap
Lake Hylia is the location of the Temple of Droplets, which is the fourth dungeon in the game. To the south is Mayor Hagen's lakeside summer cabin, but it can only be accessed by swimming south. Until you obtain the Flippers the only way to get to the cabin is to go through a cave in the center of the Minish Woods. There are a few caves and chests that can only be accessed after you get Roc's Cape or by fusing Kinstones. One of Tingle's brothers is on a ledge by the entrance. To the west is Hyrule Castle, to the south is the Minish Woods, and to the North is Veil Falls.

The Legend of Zelda: Twilight Princess
Lake Hylia is, in this game, located in the far south of Lanayru Province, in northern Hyrule. Zora can be found here, along with Fyer, a cannon expert. Above the lake is the Great Bridge of Hylia, which leads to the heart of Lanayru Province. This is the only way to reach the Gerudo Desert other then the use of the Desert Twilight Portals. In the beginning, when the Province is still covered in Twilight, the lake has been drained so that it is only a puddle. Once the water of Zora's Domain has been unfrozen, the water flows down Zora's River and the lake refills. North of Lake Hylia is the Zora's River and the Zora's Domain. The Water Temple islet from Ocarina of Time is still present, with the tree atop long dead, and in advanced stages of decay. Over the years, the Water Temple has been blocked off, with the entrance functioning as a shrine to the spirit Lanayru. The lakeside laboratory has become part of Fyer and Falbi's Watertop Land of Fantastication, and a bridge has been built from the area which, in Ocarina of Time, had featured numerous rock pillars and an entrance to Zora's Domain. This bridge, the Great Bridge of Hylia, links to the Water Temple islet, and over into the Faron province.

Geology
Though Lake Hylia is a fictional lake, aspects about it suggest it is a maar lake, a kind of volcanic cone. The evident details include:
 * Hyrule has other volcanic activity nearby, such as Death Mountain, establishing volcanism in the area.
 * The lake is small, round and very deep, typical of a bowl-shaped maar.
 * Some of the lake edges are surrounded with steep walls, typical of maar formations, formed by a maar's initial bowl-shaping eruption.
 * The lake's fairy spring island could conceivably be a man-made (or fairy-made) degassing pump, to prevent carbon dioxide from oversaturating the lake water. Such pumps work to fountain water from the bottom of the lake to the top, expelling excess gas before it can build up at the bottom. Though real degassing pumps (such as at Lake Nyos in the real world) are fountains that spray water from the lake bottom up into the air, the noted absence of a fountain at Lake Hylia could mean either that:
 * The maar is inactive. Considering Ocarina of Time and the presence of fish in Lake Hylia, this is likely.
 * The fairy spring decarbonates the water and releases the gas into the air. This is less likely, as carbon dioxide sinks in atmosphere, and would blanket the surrounding ground and lake surface with a thin layer of unbreathable air. Swimming would be impossible. This assumes that the fairy spring doesn't teleport the gas to a separate location.

The Legend of Zelda
Though it is never officially named, it has been theorized that the body of water in central Hyrule, on which Level 1 and Level 4 are located, is Lake Hylia, due in part to its resemblance to Lake Hylia in other games. Though the area around the lake is inhabited by various creatures, the lake itself seems to be inhabited solely by River Zoras.