Swimming at Maine's ocean beaches is for the hearty. The Gulf Stream, which prods warm waters toward the Cape Cod shores to the south, veers toward Iceland south of Maine and leaves the state's 5,500-mile coastline washed by a brisk Nova Scotia current, an offshoot of the arctic Labrador current. During summer, water temperatures along the south coast may top 60°F (16°C) during an especially warm spell where water is shallow, but it's usually cooler than that. The average ocean temperature at Bar Harbor in summer is 54°F (12°C).
Maine's beaches are found mostly between Portland and the New Hampshire border. Northeast of Portland, a handful of fine beaches await -- including popular Reid State Park and Popham Beach State Park -- but rocky coast defines this territory for the most part. The southern beaches are beautiful but rarely isolated. Summer homes occupy the low dunes in most areas; mid-rise condos give Old Orchard Beach a "mini-Miami" air. The best swimming beaches are Long Sands Beach at York, with a festive, carnival atmosphere along Route 1A and a long sandy strip (it disappears at high tide, however); and Ogunquit, a 3-mile-long sandy strand with a mildly remote character. See the "Portland" section later for a quick primer on the best beaches near that city.
The beaches of Maine's many lakes and rivers deserve a look if you want to spend a significant amount of time in the water during your trip; their waters are tepid in comparison to the frigid Atlantic. Some are part of state or local parks, and include such amenities as lifeguards or snack bars, but many others are completely a matter of local knowledge. Look for cars inexplicably pulled over along a road near a river or lake, and a good place to swim is probably just a short walk away. Bring insect repellent if mosquitoes, flies, or black flies bother you, and be sure it's safe to swim in a given spot before just plunging in; rough currents, a rocky bottom, and other dangers may lurk.
