The Cape Cod Rail Trail is connected to Chatham by a spur called the Old Colony Trail, which runs 4.25 miles from the Harwich bike rotary to Depot Rd near the town center. In addition, Chatham's side streets and shady lanes are well suited to cycling. Adventure Chatham can help with bike rental.
Gray and harbor seals gather in amazing hordes in Chatham's waters and haul out on the shoals. There are two ways to see them. When it's low tide, just go down to the Chatham Fish Pier and look due east to spot seals basking on the sandbars. To get closer to the action, join a boat tour: Beachcomber and Monomoy Island Ferry both have regular daily departures in summer.