Skateboarding
It was 1973-1974 that we got involved with Skateboarding.  The first neoprene wheels had were on the boards.  I was using a Hobie Board.  Here a buddy and me are skating down one of the highways off the Sierra Mountains.  Duh!

The First Skate Parks were springing up all over Southern California, and they all closed within a couple of years due to litigation.  People fell off their boards and broke their arms and then sued the facilities.  I saw early on that there would be some broken bones with this activity so we stuck to safer endeavors like hang gliding.