I recently found another portion of Town Lake that not nearly as many people seem to know about. It's immediately East of I-35 on the North side of Town Lake at Fiesta Gardens. I had heard of Fiesta Gardens before (and had even been to a few events there myself), but I never traveled passed the facility. There is a massive park on a peninsula right next to it!
HOW TO GET THERE: From most places downtown, take E. Cesar Chavez passed I-35. Take a left on Comal. Go until it hits the water.
TIPS TO MAKE THE MOST OF IT: Keep driving down the park - going East - until you hit the small boat launch. The parking lot ends and the park becomes a peninsula of grass and trees.
COST: Free