Swimming Holes Maryland's got tons of water, so much that it's springing out of the earth all over the Land of Pleasant Living, so finding swimming holes is easy. Heck, just wait for the next heavy rain and head to the nearest city sinkhole-that can't be more than half-a-block away. But if you want to go somewhere safe and legal, these are a few good options. Most are privately owned and you've got to pay for the privilege, but with that, you get sliding boards, picnic tables, grills, and water so damn cold it will freeze your bones solid. Here's a partial list: Oregon Ridge Beach in Cockeysville (13401 Beaver Dam Road,  887-1817, baltimorecountymd.gov); Beaver Dam Swimming Club (10820 Beaver Dam Road,  785-2323, beaverdamswimmingclub.com), also in Cockeysville;Rocks State Park (3318 Rocks Chrome Hill Road, Jarrettsville,  557-7994) in Harford County; and northwest of the city and possibly the best of the bunch, Cascade Lake (2844 Snydersburg Road,  374-9111,cascadelake.com), way out in Carrol County.