Canoeing on the Charles
I often see caneoists navigating the Charles River through Needham, which is quite picturesque, especially in autumn, but does have a dangerously swift current and is both shallow and narrow, at points dangerously so for this activity. Though far more enjoyable in Needham, it's probably wiser, if one desires to canoe down the river, to do so in Newton, past the falls, where the river is wider and calmer than in Needham. Then again, if one is an experienced canoeist, Needham may not prove a substantial challenge at all.
Biking is a popular activity in Needham, especially in the town's southern portions, which are less densely populated and more scenic. South Street is an especially well utilised conduit for bikers, who sometimes (and much to the consternation of drivers attempting to navigate the narrow, twisting thoroughfare) hold racing events along the street.