Lake Maggiore: 212.5 km2, 370 m at its deepest

Lake Maggiore covers 212.5¹ square kilometers and reaches 370¹ meters deep, which makes it the second Italian lake by both surface and volume, behind Garda in area and behind Como in depth.

The numbers, and where they disagree

Lake Maggiore, the Verbano, has a surface of 212.5¹ square kilometers, a maximum depth of 370¹ meters, a mean depth of 176¹ meters and a volume of 37.5¹ cubic kilometers. Its level is regulated by the Miorina dam at Sesto Calende, the Ticino and the Toce flow in, and the Ticino flows out.

Two things are worth knowing about those figures. The two CIPAIS pages give 212¹ and 212.5¹ square kilometers, and the more detailed factsheet is the one quoted here. And the elevation of the lake surface above sea level is not published by CIPAIS at all, so this page does not state one.

Depth ranks the prealpine lakes cleanly: Como 410² meters, Maggiore 370¹, Garda 350², Iseo 251². Even there a discrepancy hides. The Garda factsheet gives 346 meters where the comparative table gives 350², two institutional numbers for one lake bottom.

A basin shared with Switzerland

The catchment of Lake Maggiore covers 6,599³ square kilometers, split between Italy with 3,229³ and Switzerland with 3,370³, yet 80% of the lake surface itself lies in Italian territory.

Around 670,000³ people live in the basin and it records 12 million tourist overnight stays a year, both declared by CIPAIS as orders of magnitude rather than counts.

The cross border shape has a practical consequence. Water quality, level regulation and fishing rules here are decided by an Italo-Swiss commission, which is why the institutional data on this lake is unusually good and unusually hard to reconcile between pages.

The winter mixing has failed for ten years

In 2023 the winter overturn of Lake Maggiore stopped at 60 meters of depth, the tenth consecutive year in which it stayed within the top 100⁴ meters, and oxygen in the deep water hit the lowest values in the historical series.

That sentence is the measured signature of warming on a deep lake. A lake this size normally turns over in winter, carrying oxygen down and nutrients up; when the surface no longer cools enough to sink, the bottom stops being renewed.

Ten consecutive years is not weather. It is the reason the deep water oxygen minimum is a record rather than a fluctuation, and the figure should be rechecked against the next annual monitoring report.

The Borromean Islands are shut all winter

The Borromean Islands open on a season, and in 2026 that season ran from March 12 to November 8, with last entry at 5:00 pm until October 24 and 4:00 pm from October 25 to November 8.

From mid November to early March they are closed. This is the most useful fact about them and the one most often missing from guides, which describe the palace and the gardens as though they were available on any date you happen to choose.

Isola Bella alone costs €27.00 for adults and €18.00 for ages 6 to 15 in 2026. Isola Bella with Isola Madre is €40.00, and the combination with the Parco Pallavicino €55.00. Under 2s are always free, 3 to 5 year olds free on single tickets, and the boat to the islands is a separate purchase. See Italian lakes and Piedmont.

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