The 'Golden' color originates from the weathering of pyrite and arsenopyrite minerals found in the abandoned copper mines of Jinguashi and Jiufen.
The phenomenon is a natural consequence of the area's geological history rather than active industrial pollution, as mining operations have been defunct for decades.
The site is also known locally as the 'Benthic Sea' due to the distinct sedimentation layers visible in the water.
The water color contrast is particularly sharp during periods of heavy rainfall, which washes more mineral-rich sediment into the bay.
The nearby 13-Layer Remains was once a gold refinery processing site that contributed significantly to the region's historical mineral runoff.
The area is part of the Northeast and Yilan Coast National Scenic Area.
The Yinyang Sea is a bay in Ruifang District where the water presents a distinct contrast between golden-yellow and deep blue colors. This phenomenon is caused by the high concentration of iron sulfide and ferric ions flowing from local upstream mining sites into the ocean. The yellow sediment remains suspended in the bay due to the unique topography and slow currents, preventing immediate dilution. The site is situated directly below the Jinguashi mining area and the 13-Layer Remains. Large-scale coastal rock formations frame the view of the bay from the roadside. The contrast is most visible near the mouth of the bay where the industrial runoff meets the open Pacific waters.
The elevated viewing area along the coastal road looking down toward the bay and the 13-Layer Remains.
Visit on a clear day, as the color contrast is significantly muted during heavy overcast or stormy weather.
Bring a polarizing filter if photographing, as it helps manage the sun's glare on the water surface.
Plan your visit to coincide with a trip to the nearby Jiufen or Jinguashi old streets to maximize the route.
Do not attempt to swim in the bay, as the water is sediment-heavy and the coastal currents can be unpredictable.
