Lake Admiralty
Lake Admiralty Show map of Great Lakes Lake Admiralty Show map of New York Lake Admiralty Show map of Ontario
Location	North America
Group	Great Lakes
Coordinates	43°34′55″N 77°19′12″W / 43.582°N 77.32°W / 43.582; -77.32
Lake type	former lake
Etymology	Admiralty
Primary inflows	Laurentide Ice Sheet
Primary outflows	Mohawk River to the Hudson River
Basin countries	Canada United States
First flooded	12,000 years before present
Max. length	241 mi (388 km)
Max. width	57 mi (92 km)
Residence time	7300 years in existence
Surface elevation	178 ft (54 m)
References	Lewis CFM, Cameron GDM, Anderson TW, Heil CW Jr, Gareau PL. 2012. Lake levels in the Erie Basin of the Laurentian Great Lakes. Journal of Paleolimnology 47:493-511.

Admiralty Lake was a proglacial lake in the basin of what is now Lake Ontario.^[1][2] The shoreline of Admiralty Lake was about 20 metres (66 ft) lower than Lake Ontario. The shoreline of Glacial Lake Iroquois, an earlier proglacial lake, was much higher than Lake Ontario's, because a lobe of the Laurentian Glacier blocked what is now the valley of the St Lawrence River. Lake Iroquois drained over the Niagara Escarpment, and down the Mohawk River. When the lobe of the glacier retreated the weight of the glacier kept the outlet of the St Lawrence River lower than the current level. As the glacier continued to retreat the region of the Thousand Islands rebounded, and the lake filled to its current level.

• "Nearshore Geology". Aquatichabitat.ca. Archived from the original on 2012-01-27.
• J Terasmae, E Mirynech (1964). "Postglacial chronology and the origin of deep lake basins in Prince Edward County, Ontario". Conference on Great Lakes Research, 1964 - International Association for Great Lakes Research.