Take Exit 284 toward Highland/Alpine and go 5.5 miles. Turn left onto 5300 West, continue onto South Main Street and go about 2.5 miles. Turn left onto Fort Canyon Road and after 1 mile, you will see dirt turnouts on both sides of the road and a gated dirt road on the left. I've seen cops give tickets for parking there which I don't understand, but you may want to park on one of the turnouts a few hundred yards earlier and walk up the rest of the way. The dirt road on the left that I mentioned is the trail that leads up to the Natural Water Slide and the bike jump into the pond. Hike up the dirt road until you hit a paved road. Turn left on the paved road and keep going. You will come upon two forks, keep right at both of them. When the pavement ends and turns into a dirt road, there will be a small trail on the left which leads up through the trees to the natural water slides. If you keep going straight, cross the stream, and continue for a few hundred yards, you will come upon the pond with the bike jump on your right.
Things to bring:
A BMX bike that's been retrofitted to float: you'll probably want to test this in a pool beforehand because one water noodle isn't going to cut it. We used a water noodle, two empty gallon milk containers, and a lot of duct tape.
Tools: wrenches, pliers, hex key set, etc. for fixing anything that may go wrong while you're up there.
Water: it's a bit of a hike and it get's pretty hot.
Camera: you're going to want some proof to show your friends.