Answer
$4.7ft$
Work Step by Step
We know that
$\frac{\theta_2}{\theta_1}=\frac{n_{water}}{n_{air}}$
$\frac{\theta_2}{\theta_1}=\frac{1.33}{1.00}=1.33$
Now we can find the apparent depth as follows:
$d_{app}=\frac{d}{angular \space size}$
We plug in the known values to obtain:
$d_{app}=\frac{6.5ft}{1.33}$
$d_{app}=4.7ft$