The highly recommended Cave Connection tour enters by the Lumiang burial cave and exits at the entrance of Sumaguing Cave, after crawling, scrambling and wading through about 500 meter of very steep, convoluted, tricky and wet underground passages.
Sumaguing Cave is one of the most beautiful caves I have seen with many "live" rimstones and flowstones. Even though it is regularly visited by groups of tourists and cavers, it is still very clean.
Due to the very dangerous drop-offs at the Lumiang cave and the complicated maze of passages to reach the connection with Sumaguing Cave, it is recommended to take a local guide.
The cave guides in Sagada are well organized and professional, and the caving tours are very affordable and totally worth it.