To find the circumference of a circle, you can use the formula:
\[ \text{Circumference} = \pi \times \text{diameter} \]
Given that the diameter is 8 kilometers and using \( \pi \approx 3.14 \):
\[ \text{Circumference} = 3.14 \times 8 = 25.12 \text{ kilometers} \]
So, the estimated circumference of the circle is 25.12 kilometers.