these are the famous swan boats in the lagoon in the public garden. they are sort of a boston landmark. you can take the 15 minute boat ride around the lagoon, sitting on the benches in front of these swans. the seats you see here are for the operator of the boats, who move them forward by pedaling, similarly to riding a bike. we never did this, but it is very popular, and apparently something you do when in boston... :)
they are in operation since 1877!! something i didnt know until i read the wikipedia page about them just now... the oldest boat currently in operation was built in 1918! here you can read more about the history of the swan boats.