At the beginning of this adventure, since it was my first, I wanted to make sure that my players' characters were powerful enough to survive just in case I messed up and was giving them challenges too hard for them. In trying to help them, I overcompensated, and made them too powerful and have given them way too much treasure. As a 3rd-level party of 5, they have been destroying all of their encounters which have ranged from 4th to 6th.
They are going to have to travel down-river to make decent time to get to a certain area, so I'm wondering; would it be unfair for me to have them smash their boat up and end up in the water, losing most of their gear, so that they ave to start all over? I don't want to discourage anyone, but I also don't want this campaign to be so hack-and-slash and so disinteresting people just don't bother to show up becasue they know there isn't a challenge.