There's a parking area just outside of town. On Google Maps, the road is called Astarbravt. From the parking area, head up the dirt road for just over a mile. Once you reach the reservoir, turn slightly right and follow the gravel trail up to the peak. Once you get to the top, you'll have great views of the neighboring islands.
Alternatively, you can drive up Astarbravt and park (near the reservoir) and cut the hike in half.