The famous Swan Boats in the Public Garden, www.swanboats.com ($2.50; age 2 to 15, $1), offer another peaceful interlude. While parents sit back for the 15-minute figure-eight cruise around the lagoon (including an island where the ducks lived in the book “Make Way for Ducklings”), children will be quietly intrigued by the driver pedaling away, bicyclelike, behind the swan in the back of the boat.