We study the following problem for critical site percolation on
the triangular lattice. Let A and B be sites on a horizontal
line e separated by distance n. Consider, in the half-plane above
e, the lowest occupied crossing $R_n$ from the
half-line left of A to the half-line right of B.
We show that the probability that $R_n$ has a site at
distance smaller than m from $\mathit{AB}$ is of order
$(\log (n/m))^{-1}$, uniformly in $1 \leq m \leq n/2$. Much of our analysis can be carried out for other two-dimensional
lattices as well.