The difference between a good Cape Cod holiday with children and a frustrating one is almost entirely a matter of which water you put them in.
Families arrive with a picture in their heads of the outer beaches — the sand cliffs, the dune grass, the empty Atlantic. Those beaches are magnificent and they are the wrong place to teach a five-year-old to swim. The bottom shelves steeply, the shore break lands hard enough to knock a child over, and the water commonly sits in the low sixties Fahrenheit through July. Twenty minutes in and they are blue and furious.
Turn inside the hook and everything changes. The bay side of the Cape, from Sandwich round through Brewster and Orleans to Eastham, is shallow and sheltered and ten to fifteen degrees warmer. More than that, it does something no other coast on this network does: at low tide the water withdraws across sand flats that run out for hundreds of yards, sometimes most of a mile, leaving a warm, ankle-deep world of ribbed sand, tidal pools, hermit crabs, moon snails and channels a child can sit down in. Families who discover the Brewster and Skaket flats spend three days there and cancel everything else. It costs nothing but the parking.
The third option is Nantucket Sound along the south shore, from Falmouth through Harwich, which is the warmest and calmest ordinary swimming on the Cape and the sensible default for toddlers.
And there is a fourth that visitors rarely consider. Hundreds of freshwater kettle ponds sit inland, left behind by melting glacial ice, several of them inside the National Seashore and a cluster of good ones at Nickerson State Park in Brewster. In August they are warmer than any salt water on the peninsula, they have no waves, no current, no seals and no sharks, and they are the reliable answer on a day when the ocean is not cooperating.
Beyond the water, the Cape hands children a few genuinely unusual things: a 25-mile flat paved rail trail you can ride with a nervous eight-year-old, a granite tower you climb by ramps rather than stairs, a working fish pier with seals waiting underneath, a summer baseball league that charges nothing to watch, and boats that go out to see whales and seals.
What follows is organised by what your children are actually like rather than by what is nearest, plus the safety notes that matter here specifically — which are the cold, the shore break and the cliffs, in that order, before anything with fins.
