Lake Trojiško, formerly also called Gradiško Lake, lies below the village of Sveta Trojica in the Slovenske gorice hills. It was created in the late 1960s by damming the Velka stream. Today the lake is a distinctive part of the village landscape, overlooked by the pilgrimage Church of the Holy Trinity and its three bell towers.
An approximately three-kilometre walking trail circles the lake, offering an easy route for recreation and views across the water. Along the path are marked “energy points”, a feature of local tourism, although claims of healing effects are not scientifically established. The lake is also associated with recreational fishing. Natural water-treatment areas along its northern shore help protect the aquatic environment.
A route along the hillside beneath the church, passing the Stations of the Cross, connects the village centre with the lakeside. The area brings together walking, religious heritage and the rural landscape of Slovenske gorice. The official name Trojiško jezero has been in use since 2012.