Suggestion... Drive (or cycle) to Morell. Cycle on the Confederation Trail to St. Peters (11 km) then cycle out to Greenwich National Park (10 km). Walk through the dunes to the beach (try to avoid the boardwalk - fly right at the beginning). Round trip about 40 km.
Suggestion... Take the Confederation Trail to Montague Junction then left and into Montague (11 km). Cycle on Route 17 out to Panmure Island Provincial Park and beach and back. Round trip about 50 km.