This singletrack is fast and fun, and it has some decent changes in elevation for South Florida. Check out the upsy-downs at the beginning of the clip, and the switchbacks through the trees (starting at 50 seconds into the video).
I was riding a stretch of singletrack at West Delray Regional Park’s MTB trail. West Delray Park has one big loop that is about 2.5 miles, with a one-mile stretch of fairly technical singletrack and views that make the trail worth looping around twice. The loop passes along a lake offering two scenic vistas and then through dry hammock and finally through dark undergrowth and back along a second, smaller lake to the trailhead. On most days, a MTB rider will find him or her self having the trails pretty much to themselves at the quiet, 313-acre nature preserve. West Delray Regional Park is off Atlantic Avenue, west of U.S. 441.