Massachusetts vs. New Hampshire: Which Has the Deepest Lake?

The deepest lake in New Hampshire is Lake Winnipesaukee. At it's deepest point, Winnipesaukee is a whopping 212 feet deep. But - what about Massachusetts?

Imagine stepping into a lake and feeling the squishy, muddy bottom under your feet. That’s what it’s like at Quabbin Reservoir, the deepest lake in Massachusetts. Just how deep is the Quabbin, though?

Massachusetts has over 3,000 lakes and ponds, most about 20 to 30 feet deep. But Quabbin Reservoir, located in central Massachusetts, is special. It’s a huge man-made lake, built between 1930 and 1939. It covers 38.6 square miles, has 181 miles of shoreline, and holds 412 billion gallons of water. That’s a lot!

It’s also super deep—151 feet at its deepest point. This lake provides clean drinking water for Boston and 40 other nearby towns, so it’s really important.

Because Quabbin is a drinking water source, there are strict rules. You can’t swim, camp, bring dogs or horses, or drink alcohol there to keep the water clean. Fishing is okay in some northern spots, where you might catch lake trout, bass, or salmon. In 2016, someone caught a 25-pound lake trout! You can also boat if you have a special permit for your motorboat or rent a kayak or canoe. Groups of 25 or more people need a permit to visit.

The water can get very cold, dropping to 35–40 degrees in winter. Watch out for snakes, too—they live in the lake! Quabbin doesn’t usually flood because it has spillways, valves, and dams that let extra water flow into nearby rivers like the Swift or Chicopee during heavy rain or snowmelt. Quabbin is definitely Massachusetts’ deepest and most unique lake!

New Hampshire's deepest lake, however, is a common spot for vacationing where swimming and boating and use it's many islands are very popular. Lake Winnipesaukee, located in central New Hampshire was also the filming spot for the 1991 hit movie, "What About Bob?"