Drei Zinnen
The north–south extension of Veneto is from the Austrian border to the mouth of the River Po. By area, 29% of its surface is mountainous (Carnic Alps, eastern Dolomites and Venetian Prealps). The highest massif in the Dolomites is the Marmolada-massif at . Other dolomitic peaks are the Tre Cime di Lavaredo and the Pale di San Martino. The Venetian Prealps are not as high and range between and . A distinctive characteristic of the Pre-alps are the cave formations, including chasms and sink holes; the Spluga della Preta, situated in the Monte Lessini chain in the province of Verona, has an explored depth of , being the deepest cave in Italy. Fossil deposits are also abundant there.