Wissahickon is a spur off the Schuylkill River Trail. This is part of Fairmount Park along Wissahickon Creek. The trail will make it difficult for you to believe you are still within the city limits of Philadelphia. The trail is also called Forbidden Drive since much of it was once a road that has long been closed to cars. There are more than a few pleasant surprises along the seven mile trail including the Valley Green Inn and the only covered bridge in a US city.
There have been recent news reports of yellow jackets (bees) in the area. I have never had any issues when I have visited.
Visit Friends of the Wissahickon for more information.
For a video of one of my bike rides on Forbidden Drive in Wissahickon Valley Park visit Mark's Bike Tock on YouTube.