Fresh water there and you can use a 10.5" MF or HF DD in the mineralized sand-gravel, it looks like. With a total shoreline of approximately 288 miles there is alot of ground to search but of course narrowed down to the most popuar areas.
I had never heard of it before until now:
"Lake Winnipesaukee is the largest lake in New Hampshire."
"Lake Winnipesaukee has been a tourist destination for more than a century, especially for residents escaping the summer heat of Boston and New York City. The Native American name Winnipesaukee means either "smile of the Great Spirit" or "beautiful water in a high place." At the outlet of the Winnipesaukee River, the Winnipesaukee Indians, a subtribe of the Pennacook, lived and fished at a village called Acquadocton. Today, the site is called The Weirs, named for the weirs colonists discovered when first exploring the region. Winnipesaukee is a glacial lake and an unusual one at that, since the last glaciation actually reversed the flow of its waters. Draining the central portion of New Hampshire, it once flowed southeast, leaving via what is now Alton Bay toward the Atlantic Ocean." "Lake Winnipesaukee is the largest lake in the state of New Hampshire and the 6th largest lake in the United States that lies within the boundaries of one state. Surrounded by three mountain ranges, the wooded shoreline and crystal clear water of this spring-fed lake make it a popular year round Lakes Region resort, a place to rest and relax in beautiful surroundings. Viewing the lake from nearby Mt Major offers one of the best vantage points to seeing a great portion of this spectacular lake." "The lake contains at least 253 islands, half of which are less than a quarter-acre in size, and is indented by several peninsulas, yielding a total shoreline of approximately 288 miles (463 km). The driving distance around the lake is 63 miles (101 km). It is 504 feet (154 m) above sea level. Winnipesaukee is the third-largest lake in New England after Lake Champlain and Moosehead Lake."
http://www.winnipesaukee.com/
http://en.wikipedia.org/wiki/Lake_Winnipesaukee
http://www.lakewinnipesaukee.net/
Lake Winnipesaukee mystery stone
http://en.wikipedia.org/wiki/Lake_Winnipesaukee_mystery_stone
"The mystery stone from Lake Winnipesaukee is an alleged out-of-place artifact (OOPArt), reportedly found in 1872 while workers were digging a hole for a fence post."