Genting Island is a boat trip from Lampa Strait Port, usually arranged with local fishers. The ride is part of the day: you leave the larger island behind and move into Natuna's quieter water, where snorkeling and simple dives are the draw.
This is not a polished dive destination. Gear and guiding need to be sorted in Ranai or through local contacts, and conditions matter. When it lines up, Genting gives you the kind of clear-water island day that justifies the trouble of getting to Natuna.