Morskie Oko (Slovak: Morské oko; Hungarian: Halastó literally "Eye of the Sea") is the largest and fourth deepest lake in the Tatra Mountains. It is located deep within the Tatra National Park, Poland, in the Rybi Potok Valley, at the base of the Mięguszowiecki Summits, in Lesser Poland Voivodeship.
The peaks that surround the lake rise about 1,000 meters above its surface; one of them is Rysy (2,499 meters), the highest peak in the Polish Tatras. Beside Mięguszowiecki Summits (including Mięguszowiecki Szczyt Wielki, 2,438 meters), farther away and slightly to the left, is the distinctive, slender Mnich (“Monk,” 2,068 meters). Many Swiss Pines also grow around the lake.
Morskie Oko is one of the most popular destinations in The Tatras, often receiving over 50,000 visitors during the vacation season. It is reached by foot in about two hours from the nearest road that allows motorized access. Many other tourists opt to take the journey by horse-drawn cart, a large number of which are operated by the local Górale inhabitants. In winter, a short section of the journey is in an avalanche danger zone, and the area can remain cold and rainy even in summer. In the advent of its popularity, visitors have been forbidden from swimming in the lake or feeding the trout.