Shannon B.
Yelp
True story, bro. More than a couple of decades ago, two dear friends (one who is no longer with us, but that's a saga for another time) got a wild hair in their drunken 19-year-old heads and did something very stupid. They jumped off this steel arch bridge in the middle of the night and somehow lived to tell the tale.
Actually, the first one jumped, hit the water 100 feet below in an unintended sitting position, and cracked his coccyx and L2 vertebra before plummeting under the dark surface of Lake Austin. When he came back up for air, he hollered to his friend, "Don't do it, don't do it!" and a potential Darwin award was put away for another day. Ever since, whenever we pass this beautiful, award-winning bridge or see an image of it, the topic of that juvenile dumbassery comes up and we marvel at how he is still alive with the use of all 4 limbs, albeit with a pesky recurring back pain to remind him of youthful folly and close calls.
Don't you be like that dumbass! If you don't get hurt, you'll still get a $200+ fine if you're caught (and you can be sure that someone will be filming). In case you need more convincing, here are just a few stories of people being injured or worse doing dumb things near the Pennybacker (aka 360) Bridge:
https://www.statesman.com/news/local/scenic-view-near-pennybacker-bridge-can-dangerous-deadly/En1TRzkvTMl4VtTduEStrN/
https://www.kvue.com/article/news/local/man-suffers-critical-injuries-after-diving-into-shallow-water-near-360-bridge-atcems-says/269-529954665
https://www.reddit.com/r/Austin/comments/32xq2y/mans_body_found_floating_near_pennybacker_bridge/
https://www.austinbassfishing.com/forum/miscellaneous-info/25531-pennybacker-bridge-jumper-drowns.html
What you *do* likely want to do is bring your camera or smartphone out here to get some lovely pictures of some iconic Austin scenes from the cliffs above the northwest corner or from the bridge itself. Sunrise and sunset are always good times for that, but just about any time of day, you'll find folks out here trying to get that perfect shot. Our family has taken professional portraits out here more than once, as well. Of course, we don't do anything to interfere with traffic, cause an accident, or wind up in the hospital. We're older and wiser these days!
Keep in mind that the "360 Bridge Overlook" area on the cliff off Shepherd Mountain that is accessible by a rocky 5-minute climb from the "no parking" area is not (yet) a public park, regardless of how many people you may see up there. You are entering at your own risk; wear appropriate footwear, observe sensible "rules of the trail", and be a good steward (leave no trace).
If you'd like to see this space (formally known as the "Camelback Tract", now owned by the guy who founded 1-800 Contacts) become a legit public park that can safely be enjoyed for generations, check out the 360 Bridge Park site to learn how you can help. https://www.360bridgepark.com/
Be careful where you park and make sure it's not in a "no parking / right of way / ROW", "tow away", or "falling rocks" area (although you'll likely see plenty of cars doing just that). Parking enforcement has become very strict these days due to bad behavior on the part of some visitors AND the massive perpetual traffic jam that exists most days on Loop 360 (aka Capital of Texas Highway). Depending on the time of your visit, you may find free street parking on Bridgepoint Parkway (but heed the signs; not all of the street allows parking). Some of the nearby office complexes off West Courtyard Drive and Plaza on the Lake also offer fee-based parking that won't result in a ticket or worse. You should also be aware that opportunistic car break-ins are not uncommon at the "no parking" area near the trail to the top, so don't leave anything of value in your vehicle if you do decide to park there.
If you have a boat (or are meeting a friend who is kind enough to take you for a ride), you'll be under the bridge at the Travis County-managed Loop 360 Boat Ramp. More info about parking fees and rules are here:
https://parks.traviscountytx.gov/find-a-park/loop-360-boat-ramp