Lake Maggiore is 64.37 km (40 mi) long, and 3 to 5 km (2 to 3 mi) wide, except at the bay opening westward between Pallanza and Stresa, where it is 10 km (6 mi) wide. It is the longest Italian lake, although Lake Garda has a greater area. Its mean height above the sea level is 193 metres; a deep lake, its bottom is almost everywhere below sea-level: at its deepest, 179 metres below. Its form is very sinuous so that there are few points from which any considerable part of its surface can be seen at a single glance. If this lessens the effect of the apparent size, it increases the variety of its scenery. While the upper end is completely alpine in character, the middle region lies between hills of gentler form, and the lower end advances to the verge of the plain of Lombardy. Lake Maggiore is the most westerly of the three great southern prealpine lakes, the others being Lake Como and Lake Garda.
The lake basin has tectonic-glacial origins and its volume is 37 cubic kilometres (9 cu mi). The lake has a surface area of about 213 square kilometres (82 sq mi), a maximum length of 54 km (34 mi) (on a straight line) and, at its widest, is 12 km (7 mi). Its main tributaries are the Ticino, the Maggia, the Toce (by which it receives the outflow of Lake Orta) and the Tresa (which is the sole emissary of Lake Lugano). The rivers Verzasca, Giona, and Cannobino also flow into the lake. Its outlet is the Ticino which, in turn, joins the river Po just south-east of Pavia.
The lake’s jagged banks are surrounded by the Pennine and Lepontine Alps, and Lugano Prealps. Prominent peaks around the lake are the Gridone, Monte Tamaro, Monte Nudo and the Mottarone. The highest mountain overlooking Lake Maggiore is Monte Rosa (4,634 m, 15,203 ft), located about 50 kilometres (31 mi) west of it. The western bank is in Piedmont (provinces of Novara and Province of Verbano-Cusio-Ossola) and the eastern in Lombardy (province of Varese), whereas the most northerly section extends 13 kilometres (8 mi) into the canton of Ticino, where it constitutes its lowest point above sea level as well as that of Switzerland. The culminating point of the lake’s drainage basin is the Grenzgipfel summit of Monte Rosa at 4,618 metres (15,151 ft) above sea level.