Lake Bohinj, covering 318 hectares (790 acres), is the largest permanent lake in Slovenia, located within the Bohinj Valley of the Julian Alps, and it is part of Triglav National Park. The church of St John, The Baptist is on the northern side of the Sava Bohinjka river across the stone bridge, is what every medieval church should be: small, on a reflecting body of water and full of exquisite frescoes. The nave is Romanesque, but the Gothic presbytery dates from about 1440. Many walls and ceilings are covered with 15th- and 16th-century frescoes. On the lower walls of the presbytery are rows of angels, some with vampire-like teeth; look for the three men above them singing. They have goitres, once a common affliction in mountainous regions due to the lack of iodine in the diet. Lake Bohinj is 4.2 km (2.6 mi) long and 1 km (0.62 mi) at its maximum width. It is a glacial lake dammed by a moraine. The clear waters are the habitat of brown trout, burbot, European chub, common minnow and Arctic char, eight genera of mollusks. Bohinj is a valley that stretches from Soteska to Ukanc. On the south side, it is enclosed by the Lower Bohinj Mountains, which rise to 2.000 meters, and on the north by the Triglav mountain range with Mount Triglav, Slovenia`s highest mountain (2864 m). Much more water leaves Lake Bohinj than enters it, which is explained with subterranean sources of water. Holy Spirit Church by the Lake The succursal church beside Lake Bohinj was built in the second quarter of the 16th century, but the archives mention a church here in the second half of the 15th century. The style is Baroque. Its special features include a roof in the shape of a camel's back, which is linked to a local legend, and the fresco of St. Christopher on the exterior north wall by the painter Matija Koželj.