The first thing to understand about paddling here is that the water leaves. In Cape Cod Bay the tide moves something like nine or ten feet between high and low, and the salt marshes behind the barrier beaches are built to drain. A creek that is forty feet wide and chest deep at ten in the morning can be a gutter of mud with a foot of water in it by two in the afternoon. Paddlers who learned on a lake or on a southern estuary with a three-foot range get caught by this every single summer, and the consequence is not danger so much as a very long, very undignified drag.
So the tide table is the planning document. Everything else follows from it.
The second thing is temperature. This is the North Atlantic. Sea temperatures on the outer shore often sit in the low sixties Fahrenheit in July and are much colder in spring and autumn, which puts a capsize into a different category than it occupies further south. Cold shock is a real mechanism and it does not care how well you swim. Massachusetts reflects this in law: paddlers are required to wear a flotation device, not just carry one, between the middle of September and the middle of May. Check the current regulation before a shoulder-season trip, and wear it anyway in June.
With those two facts in hand, the Cape opens up into three genuinely different kinds of paddling. There are the salt marshes and tidal creeks behind the barrier beaches, Nauset at Eastham being the best of them, where you thread a channel through spartina with terns overhead and the ocean audible on the far side of the sand. There are the sheltered bays and harbours, Pleasant Bay above all, which is the Cape's largest estuary at somewhere around nine thousand acres and big enough to paddle for days. And there are the kettle ponds, hundreds of them, freshwater holes left by melting blocks of glacial ice, with no tide, no current, no seals and water ten to fifteen degrees warmer than the sea.
That last category is the one visitors underuse. After three days of failing to get into the Atlantic past your knees, a pond at Nickerson State Park in late August is a revelation.
One route is simply off the list. Do not paddle the Cape Cod Canal. It runs a strong reversing current, it carries commercial shipping in a confined channel, and it is federally managed water. Admire it from the service road on a bicycle.