Accesa lake, located 157 m above sea level, has a perimeter of approximately 1850 m. The lake, fed by the river Bruna; is found in a depression of Carsic origin that was formed in the limestone rocks of the so-called “cavernous limestone” formation, approximately 220 million years old. The lake’s source is under the lake’s surface, specifically in the southwestern sector, locally known as “Inferno”, or Hell. Between 1995 and 1996, the lake was the subject of exploration and studies that established, once and for all, its maximum depth of 37.6 m near the center of the lake. At every point and at any depth, the lake floor is covered by a thick silt layer created by the erosion of the hill surrounding the lake basin. Underwater exploration in the so-called Inferno also confirmed the presence of a thick sediment layer on the bottom of this area. From a depth of 13.4 m the lake floor, in fact, consists of a series of depressions containing sand and gravel; a spring filters through the bottom of these depressions: this is the underwater source of Accesa lake.

Accesa lake is a fishing preserve of the Federazione Italiana Pesca Sportiva (Italian Federation for Sport Fishing). Its waters, that according to local tradition never freeze, are home to a wide variety of fish species, such as carp, tench, pike, chub, perch, bleak, eels and trout, while many varieties of water fowl nest among the reeds and rushes that line the shore. Swimming is allowed in the lake, but boating is forbidden.