Phraya Nakhon Cave, Thailand

Phraya Nakhon Cave stuns with a collapsed ceiling forming a natural skylight that illuminates a 19th-century royal pavilion built for King Chulalongkorn in 1890—a feature more photogenic than the gypsum chandeliers of Lechuguilla Cave. Sunlight streams in for roughly 3 hours daily, enhancing the pavilion's intricate Thai architecture. Located in Khao Sam Roi Yot National Park, entry requires a 430-meter jungle hike, which makes it 25% more accessible than Lechuguilla's research-only access.