Tasman Lake, Glacial lake in Mackenzie District, New Zealand

Tasman Lake is a proglacial lake at 715 m in Aoraki / Mount Cook National Park, Canterbury, on New Zealand's South Island. It lies at the terminus of the Tasman Glacier, which retreats north into the lake; the Murchison River enters the lake. By 2008 it measured about 7 km long, 2 km wide and 245 m deep.

Small meltwater pools on the Tasman Glacier's surface began merging in the 1970s and formed this lake by 1990 as the glacier retreated. The accelerating ice melt has continued to enlarge the lake significantly since then.

The lake's name honors Abel Janszoon Tasman, the first European explorer to reach New Zealand's shores in the 17th century. Today, it stands as a place where visitors can directly witness the ongoing effects of glacier retreat and environmental change.

The lake is best reached via a short walking trail from the parking area at the end of Tasman Valley Road. Morning or early afternoon visits offer the best light conditions and generally fewer crowds on the path.

Since 2006 a 50–60 m apron of submerged ice has projected from the glacier's terminal face, and icebergs break off it to drift the length of the lake. The lake deepened to about 245 m by 2008 and is expected to reach roughly 16 km in length within one or two decades.