Al Qiyam Mosque is one of the older religious sites in the Natuna Islands, on Pulau Tiga rather than the main island around Ranai. The mosque is modest, but the surrounding graves and the stories attached to them make it a worthwhile stop if you are already exploring the outer islands.
Access depends on local boat arrangements and local help. Dress respectfully, ask before entering, and treat the cemetery as part of the visit rather than just a backdrop.