Puslinch Lake, Kettle lake in Wellington County, Ontario, Canada

Puslinch Lake is a kettle lake in Wellington County, Ontario, the largest of its kind in North America. It measures about 2.7 km north to south and 1.8 km east to west, with a surface area of 1.6 km² at 303 m above sea level. Most of the lake is less than 2 m deep; the maximum depth is about 5.5 m, and the deepest zone covers only 0.4% of the lakebed.

Peter and Alex Lamont were the first permanent settlers, arriving in 1831 after the area was surveyed into farm lots. In 1846 Father Simon Sanderl built a small mission church on Big Island; by the late 1850s two men had converted it into a hotel. Guelph brewer George Sleeman bought land in the 19th century, built the Puslinch Lake Hotel in 1880 and ran a steamboat until 1883.

The lake's name does not come from a surveyor; the area was surveyed into farm lots before permanent settlers arrived in the 1830s. Since the late 1880s it served as a summer playground for Wellington and Waterloo counties. Barber's Beach, called Swastika Beach until 1938, drew day trippers for decades; its road, Swastika Road, kept its name after a 2017 council vote.

The beach and boat launch closed in July 2020 after the owners found visitor numbers overwhelming the small site; the Township of Puslinch said in October 2020 it was working towards creating public access. As of February 2021 the township described Puslinch Lake as a public lake with no formally maintained public access. Check the current situation before travelling, and note that the lake is reached from Wellington County roads southwest of Guelph.

The water holds around 16 different fish species, including a rare population of banded killifish that is seldom found elsewhere in this part of the region. This small fish population makes the lake worth noting for nature watchers.