Taroko Swallow Grotto Trail (燕子口步道, Yanzikou)
The walls on each side of the river contain caves which form natural nesting places for spring swallow birds, bringing life to the area nearby the roaring river, with locals naming it Swallow Grotto.
The path is shared between pedestrians and automobiles (one-way traffic), and a tunnel is located south of the primary trail running parallel for main traffic.
Sights along the trail include the Indian Chieftain’s Profile Rock (印第安酋長石), potholes (壺穴) along the cliff face, swallows darting in, out, and around the caves, ultimately leading up to the Jinheng Park (靳恆公園) and Jinheng Bridge (靳恆橋). Walking from the Buluowan-Swallow Grove Trail to the Jinheng Bridge takes around 20 minutes. Due to frequent landslides and falling rocks, it is advised to wear a safety helmet, available for free from the park.
When standing near the middle of the grotto, it’s possible to see two vastly different views on the east and west. The east side of the grotto is more flat, with yellow-brown metamorphic gneiss rock, while the west side is steeper with primarily grey-black marble rock. The differences in landscape are due to the erosive power of the Liwu River (立霧溪) and its effect on the rock. The upstream marble is more resistant to erosion, creating a narrow and steep gorge, as opposed to the downstream gneiss rock which is more easily eroded, creating a wider, flatter landscape around the riverbed.
Located close to the grotto is the Zhuilu Old Road (錐麓古道, Jhuilu Old Road), previously part of the Cross-Hehuan Mountain Road during the Japanese era, and was built in 1914 following the end of the Battle of Taroko to control aborigine villages. This 10.3KM long, 90CM wide trail begins at the Cimu Bridge (慈母橋) and reaches heights of 500M above the Liwu River. The road ends at Swallow Grotto by crossing a suspension bridge back to the main road PH8. Mountain and park entry permits are required to hike this difficult path, and visitor count per day is limited.
Refreshments and restrooms are available at the Jinheng Park (靳恆公園).
The Ludan Bridge (魯丹橋) is located along the tunnel portion of the highway and crosses over the Ludan River (魯丹溪).