Montana - the name means 'Mountain' and that sets the backdrop for all the top summer fun in this state.
State parks are usually the main summer outdoor attraction in Big Sky Country with Whitefish Lake State Park heading the list with a sandy beach for relaxing the day away surrounded by the majesty of the Rocky Mountains.
Other top lake beaches throughout the state include Fresno Beach (yes, in Montana - near Havre). Other popular "hot spots" with locals and visitors alike.Black Sandy Beach in Helena, and Cooney Beach near Laurel.
Glacier and Yellowstone National Park are also familiar names, but there are plenty of hidden treasures in these mountains for lovers of wet-n-wild adventures.
Have fun!
More about Montana lake beaches around the Web:
Montana
State Parks - This Fish, Wildlife and Parks site is a bit difficult to navigate if you don't know what you need. The search is great... just type in boating or swimming and you'll get a useful list.
Libby,
MT - The photos alone are worth a visit , but the info on places to fish, swim, water-ski or enjoy other outdoor recreation is the real draw,
with detailed facts and driving directions.