Description
The main tunnel (the section of the complex most frequently visited during the year) winds towards the SSW for about 1,500 metres until it reaches the area of the Marighetti Shaft and the Ramo dei 4 Laghi. The entrance is followed by a long downhill, siphon-like section, normally filled with water. Leaving the mouth of the Ramo del Grillo to the right, the gallery begins to climb again until it reaches Piazza Selva, a large inclined interstratum hall into which the Ramo del Cigno flows (we are approx. 400 m from the entrance) and from which the Galleria Inferiore and the Ramo delle Sabbie start.
The semi-touristic tour of the Swan Branch (spectacular for the beauty of the concretions) soon stops at the lake-siphon of the same name. Towards the east, one can descend the Primo Pozzo (a small fissure a few metres deep) and enter the Galleria Inferiore under the Grande Diaclasi. Pass the entrance to the Ramo Giuliani on the left (very dangerous with sudden rains) and you will soon reach the Grande Lago (a lake-siphon that measures more than 25 metres in length and 2-3 metres in depth during lean periods). After passing it with a dinghy (only in the dry season), climb up to Lago Scuro (another lake-siphon with similar characteristics to the previous one) after passing, on the right, the start of Ramo Bellin. The cave continues southwards with alternating ups and downs (section always quite large, 6- 7x2-2.5 m) and finally reaches Pozzo Marighetti (33 m).
Access and main data Grotta della Bigonda ( VT-TN-243)
It opens just above the hamlet of Selva di Grigno (right side of Valsugana), on the right bank of the river Brenta, not far from the Trento-Vicenza border, at the foot of the Altopiano dei Sette Comuni.
Karstic Area: VT SC 16 - TN
Entrance altitude: 470 m
Height difference: +350, -108 m
Real development: > 30000 m
For further information: Gruppo Grotte S.A.T. Selva, 38050 Grigno Valsugana (TN)
Bibliography:
1) La Grotta della Bigonda n. 243 VT in Valsugana / Antonio Galvagni. // IN: Studi trentini di scienze naturali. Trento. V. 44 (1967), no. 1
2) A brief history of the explorations in the Grotta della Bigonda / Gruppo grotte S.A.T. Selva. // IN: Natura alpina. Trento. V. 42 (1989), no. 2/3; p. 159-161
3) Proceedings XI Regional Conference on Speleology of Trentino-Alto Adige / edited by the Rovereto "E. Roner" Cave Group. - Rovereto (TN) : Osiris, 2001. - 241 p.
4) Proceedings of the 12th regional conference on speleology in Trentino-Alto Adige : Grigno, 7-8 September 2002 / [edited by: Marco Ischia]. - Trento : Society of Mountaineers of Trento, Mountain Library, 2004. 167 p.
