Parking: $5
Swimming: Free
Running: Free
Seeing a 2008 Olympian in Triathlon practice: priceless

There are some things you can see on the Charles. For everything else, there's Walden Pond.

Bottom: Jarrod Shoemaker, 2008 US Olympic team, Triathlon
Top: Ethan Brown, 2007 US U-23 Triathlon Champion