The Mammoth Lakes Basin lakes easiest to access are Twin Lakes, Lake Mary, Lake George and Horseshoe Lake. You can visit these lakes in the summer months via Lake Mary Rd. Visitors come to fish and boat, and hiking trails can be found at some of these lakes, too. All allow kayaking and canoeing, except for Horseshoe. Horseshoe, though, is the only one where swimming is permitted. Note the signs in certain areas of Horseshoe warning about pockets of highly concentrated carbon dioxide gas in the soil.