The five largest and most densely settled islands are Fukue, Hisaka, Naru, Wakamatsu, and Nakadōri. All have mountainous interiors. Intensive dry-land farming is practiced on terraces and slopes, and there is irrigated wet-rice cultivation on the few slender coastal plains. Fishing (mackerel and cuttlefish) is the main activity for ports, including Fukue (Fukue Island) and Narao (Nakadōri Island). The economy of the northern half of the archipelago, centred on Sasebo, Kyushu, is based on fishing. Agriculture (barley, loquats, and sweet potatoes) predominates in the southern islands, which are connected by regular ferry service to Nagasaki. Tourism has grown in importance.