We no longer allow our kids to ride their trail bikes around local bush reserves because of the impact on others. They had great fun but a lot of people did not appreciate the noise pollution so it has been stopped. I feel jet skis fall into this category. A couple of ski's belting around can ruin great spots like the Wrecks or Horshoe bay for hundreds of other recreational users. At a bare minimum they should be made to be much quieter.
Neil