The 250 bus on the return from Untersburg passes by Hellbrun, with the bus stop clearly announced and having the advantage of being the exact same stop to get the return to Salzburg as its a circular route. We, two adults, visited as we were near, it was hot and we had a Salzburg card. It is really good that the bus and entry is included in the card. The visit to the trick fountains is great fun, you do get a little wet (some more than a little) but on a sunny day it was great, a chance for grown ups to 'play' have fun and laugh. If you don't laugh I recommend you stay at home! The engineering involved at the time it was made makes it more astounding. The grounds are beautiful, you could easily spend a day, picnic, park etc and the Sound of Music gazebo.