It styles itself as a sort of "Hawaii of Japan," and does exude a peaceful atmosphere. It is famous for it's flowery botanical garden, proximity to the tranquil Ikeda lake (池田湖) and the green conical mount Kaimon （開聞岳）, and a small island with a disappearing sand walkway called Chiringashima (知林ヶ島). Yet, it's the natural hot springs beneath the beach called "sunamushi" (砂蒸し), roughly translated as a sand bath, that is the town's biggest claim to fame. If you're daring or curious enough to try being buried in steaming hot sand as a kind of luxury spa experience, you'll find a most interesting chance here.
Chiringashima is a small, uninhabited island with a sand walkway that appears at low tide. From March to October, a sandbar of about 800m allows you to walk across part of Kinko Bay to the island in about 20 minutes. The longest time the walkway appears for is four hours. According to city statistics, the walkway appears for over an hour 190 days a year, and 86 days a year it appears for more than two hours. The island is 3km around and 90 meters tall at its highest point. This sandbar is occasionally washed away after typhoons and disappears for a while, but it is restored when sands are brought back by the tide. The plant Vincetoxicum austrokiusianum, which is listed as an endangered species in Red data book, has been found on Chiringashima. On the island, there are esplanades and an observation deck. This island is known as a matchmaking spot for couples. Fishing or gathering shellfish is possible.
Ibusuki's botanical garden.
Climbing Kaimon-dake (開聞岳), or Mt. Kaimon makes for an incredible view on a clear day. From the very flat land and lake below, to the smoking Sakurajima to the north, to the peaks of Yakushima in the ocean to the south, there is plenty to be seen. There's no better follow up to the 4 to 6 hour hike than a day in Ibusuki's hot springs resorts. You can access the trail head by bus (you'll want to get of at Tozan Iriguchi (登山入り口)), or alternatively, by a very short walk from Kaimon's train station, which is nothing more than a platform and bench that can be reached after a short train ride from Ibusuki's train station.
The "sand bath" and related spas.
"Nagashi somen" (流し素麺) is a fun experience of a meal in the warm weather, and involves grabbing swirling noodles from a small circular stream of water at your table.