To find the circumference of a circle, you can use the formula:
\[ C = \pi \times d \]
where \( C \) is the circumference and \( d \) is the diameter of the circle. Given that the diameter is 8 kilometers and using \( \pi \approx 3.14 \), the calculation would be:
\[ C = 3.14 \times 8 \]
Now, performing the multiplication:
\[ C = 25.12 \]
Thus, the estimated circumference of the circle is 25.12 kilometers.