Cryptodepression

Prealpine lakes in Northern Italy by elevation (surface and deepest point elevation). Lake Maggiore, Lake Lugano, Lake Como, and most of all Lake Garda have depths in cryptodepression

A cryptodepression is the portion of a lake which lies below sea level^[1] (Greek κρύπτoς, 'hidden' + depression).

Description

A cryptodepression is often due to creation of a rift valley or a glacial lake.^[2]

Lakes are often long and narrow. Further, the surrounding landscape and the shore of the lake can be very steep.^[3]

Examples

Simple calculation example:
Lago O'Higgins/San Martín
Surface elevation  250 m -
Maximal depth      836 m =
_________________________________
Cryptodepression  -586 m

• Glacial lakes and moraine-dammed lake: major prealpine lakes in Italy have cryptodepression created by erosion. On the contrary, on the other part of the Alps, Swiss, Bavarian and Austrian lakes don't, because of their significantly higher surface elevations.

• Rift valleys: the deepest known cryptodepressions all over the world is in Lake Baikal (-1200 m).^[4]

References

Look up cryptodepression in Wiktionary, the free dictionary.