Sedanau is the most interesting settlement excursion from Great Natuna if you want people and harbour life rather than another beach. A large share of the village is built over the water, giving it a stilt-house feel that Wikivoyage compares to Brunei's Kampong Ayer.
Go slowly and respectfully. This is a lived-in fishing community, not an open-air museum, and the reward is in the walk: boats tied under houses, shopfronts facing the water, and the practical architecture of an island town.