Peterborough is pretty small and flat, so getting around is relatively easy. Biking is popular, though the winter months can be a challenge. There is a pretty good bus system, a number of taxi services, and of course one can drive or walk almost anywhere. OpenStreetMap has a pretty good map of Peterborough - though it can always be improved.
Take Highway 401 east to Highway 35/115 Turn north on Highway 35/115 At the junction of Highways 35 and 115, turn right on Highway 115 Exit at The Parkway/Sir Sandford Fleming Drive and continue north on The Parkway Turn right at Clonsilla Street, this will lead to downtown Peterborough
Take Highway 417 west to Highway 7 Take Highway 7 west towards Peterborough In Peterborough, Highway 7 becomes a freeway, Highway 7/115 Exit at The Parkway/Sir Sandford Fleming Drive and continue north on The Parkway Turn right at Clonsilla Street, this will lead to downtown Peterborough
Take Highway 401 west to County Road 28 in Port Hope Turn north on County Road 28 Turn east on the freeway Highway 7/115 Exit at The Parkway/Sir Sandford Fleming Drive and continue north on The Parkway Turn right at Clonsilla Street, this will lead to downtown Peterborough
Take Highway 7 east from Lindsay Continue to "Sherbrook Street West", turn left (going eastbound) on Sherbrook Street West
Bus service operates every 40 minutes from downtown Peterborough to various points in the city. Additional buses run to Trent University during the school year. http://www.peterborough.ca/Living/City_Services/Transportation/Transit.htm
See also the information at http://cptdb.ca/wiki/index.php?title=Peterborough_Transit
GO Transit operates an express bus from Oshawa GO station to downtown Peterborough and Trent University 7 days a week. At Oshawa GO station connections are available to trains to downtown Toronto, other GO bus routes, and Durham Region Transit. - http://www.gotransit.com/publicroot/en/schedules/lstserdt.aspx?table=88&station=&new=
Greyhound operates bus service to various destinations please see their website at http://www.greyhound.ca/ .
A general aviation airport exists south of the city - there is currently no scheduled service to it.