Beigan Island Introduction
Penghu has two islets named Tiezhanyu (Iron Anvil Islet) due to their resemblance to an anvil. The northern Tiezhanyu, which belongs to Baisha Township, is located off the northwest coast of Penghu Island. It is an uninhabited island primarily composed of basaltic tableland, surrounded by steep sea cliffs. The basal columnar basalt is more fragile, and under the influence of the northeast monsoon, the northern shore's rock layers have been eroded by sea currents over time, forming a massive sea cave that even small boats can enter. This cave is larger than the Blue Cave at Xijiyu and is the largest sea cave in Penghu. Inside the cave, sunlight does not reach, resulting in temperatures that are three to five degrees lower than those outside, thus it is also known as the "Air Conditioning Cave." Upon reaching the island, visitors can not only see the platform-like basalt but also unique honeycomb rocks and basalt joint furrows formed by water erosion, which are distinctive features of Tiezhanyu. This area has also served as a military shooting range, leaving behind numerous iron pieces and rock fragments. Due to the shallow intertidal zone and the lack of surrounding platforms, very few people come here, allowing thousands of birds to breed and inhabit the island, with the most numerous being the Black-naped Tern. Whenever a boat approaches, the Black-naped Terns emit alarm calls and circle in groups above, as if to remind visitors that they are the true owners of this place.
