I would have to be completely stuck before I'd call for help, but if I ran across someone else who was in trouble I would err on the side of caution without a moments hesitation and call.

Heather, it is still hard for me to imagine a group of that many adults all standing there doing nothing. Could they really have all been in shock? They were just standing on the shoreline, not more than 15-20 feet away from where those two were in the tree.

I still am amazed at their behavior. I just can't imagine doing nothing.