To find the circumference \( C \) of a circle, you can use the formula:
\[ C = \pi \times d \]
where \( d \) is the diameter of the circle. In this case, the diameter \( d \) is 8 kilometers.
Using \( \pi \approx 3.14 \):
\[ C = 3.14 \times 8 \]
Calculating this:
\[ C = 25.12 \text{ kilometers} \]
Therefore, the estimated circumference is \( 25.12 \) kilometers.