NOTE:
The Yanzikou (Swallow Grotto) trail is closed due to severe damage caused by 403 Earthquake and typhoons in 2024. On April 3, 2024, a magnitude 7.2 earthquake struck Hualien, followed by the impact of Typhoon Kong-rey on October 31, causing severe damage to the park east section of Taroko Gorge including this trail.
Following the Central Cross-Island Highway, at Yanzikou (Swallow Grotto) the rock cliffs of the Liwu River gorge seem to reach to heaven while the river runs its swiftest and the distance between the gorge walls so narrow that they almost seem to touch each other.
Along the Yanzikou (Swallow Grotto) trail which runs about a half kilometer starting from the entrance to Swallow Grotto to the Jinheng Bridge, you can enjoy the sights of the Liwu River from nearly straight above the water, the potholes on the cliff faces, the springs sprinkled along the lower parts of the walls, as well as the famous rock formation "Chieftain's profile rock".
As of early 2005 the Yanzikou (Swallow Grotto) Trail was separated from the highway by a simple concrete divider. The road was narrow, resulting in frequent congestion in the area. Consequently, the Park Administration set about building a two-lane tunnel for vehicular traffic to let walkers enjoy the sights of this spectacular part of the gorge uninterrupted by cars and buses. There are two Swallow Grotto (Yanzikou) tunnels, linked by Ludan Bridge- were completed in June 1, 2007. West-east vehicular traffic must use the tunnels. The old highway is now a pedestrian path and is also open to vehicular traffic going west (Taroko heading to Tianxiang) only that must proceed slowly.