I’m certain that Nishinoshima Island is the best island for adventure travel. The crystal clear blue waters around the island make for amazing water sports and sightseeing cruises. It has everything: mountains, hiking treks, private inlets for kayaking, snorkeling, diving, and so much more…There are also a range of mountain activities in the area, particularly trekking to Kuniga. Here are my favorite areas of the island to stay and explore.
Beppu Port
Beppu Port is the entry point to Nishinoshima Island. Large ferries and small inter-island ferries arrive here. The local tourism association (information center) is located in the port building. They have English information and rental bicycles, and nearby is a rent-a-car company. There are cafes, minshuku inns and hotels, restaurants, souvenir shops and fishing tackle stores.
Sea Kayaking
Nishinoshima Island is renowned for having some of the best opportunities to experience marine wildlife. Some fish from the south sea gather around Oki Islands. One of the best ways to see it all is to hop on board a kayak and discover this from above water, with a clear view down below. 
The Tsushima current distributes one of Japan’s biggest and warmest currents and this has the effect of ensuring a warm climate with moisture all year around. Sea Kayaking by Club Noah Oki is available from May to November. We joined a tour from 9:00-11:30 with two other groups and we could see down to a depth of 12-20 meters in the sea.
Kuniga Coast Tour Boat
The Kuniga Coast (7 km) is one of the most photographed places in the Oki Islands. You can explore the coast by sightseeing bus (scheduled services April to October) and walk up. If you want to see Kuniga Coast but you’re not in the mood for hiking, hop on board the Kuniga Tour Boat for a total cost of 2,500 yen. In 90 minutes you will reach right under the cliff and this position gives a stunning, iconic view of the hill from the water. The best time for taking photos is in the afternoon. We joined the Kuniga Coast Tour Boat in the morning, so I got too many reflections.
We boarded the ship from Urago Port to the open sea on the west side of the island, passing through the canal (340 meters), constructed in 1915. Before the canal construction, people carried their ships from the open sea to the inside sea.
Up until we boarded the ship, the Kuniga Coast Tour Boat hadn’t set sail in a week due to the effect from the typhoons. The surf was up but the captain took us to the dark sea cavern “Akekure no Iwaya” (250 meters) where two caves connect as a dogleg. It was very narrow and the hull hit the ceilings and walls of the cave but finally we passed through the cave.
Sotohama Beach
There are two main swimming beaches in Nishinoshima, Sotohama Beach and Mimura Beach. As one of the most family-friendly beaches on Nishinoshima Island, Sotohama Beach is our favorite with its crystal clear waters and perfect waves. It is open for swimming from July to August. The rocky shore at Mimiura Beach is a great place to snorkel.
Fishing
Literally everywhere, you can go fishing. I borrowed fishing rods on Dogo Island before traveling to other islands. On Nishinoshima Island, you can borrow fishing rods at SAKURAYA near Beppu Port.
We started to go fishing from 17:00 every evening and got many horse mackerels. It is better to ask the inn’s owner whether they can cook the fish. We asked the owner to freeze our catch and then sent it home.
Hiking on Matengai Cliff
There are stunning views along the 2-hour walking trail from the top of the 257-meter high Matengai Cliff. We can see horses and cows grazing peacefully in the fields along the way.
Takuhi Shrine Hiking
Takuhi Shrine is one of the oldest shrines and it is dedicated to a deity of marine safety. The main worship hall, reconstructed in 1732, is underneath the cliff face. It’s a 20-minute drive from Beppu Port, and a 20-minute hike to the shrine (one way).
Stay: Fukuro Minshuku Inn
Urago Port area is an affluent residential neighbourhood situated right on the water, making it the perfect place to take a walk to see the sunrise. At the Fukuro Minshuku Inn, you can enjoy local dishes with sea urchins and horned turban shells. Fukuro has a few rooms on offer and one dining room to share. The owner couple have created such a warm atmosphere and offered a homely experience.
We have a distance to drive between Fukuro Minshuku Inn and Beppu Port, but in front of the accommodation there is an embankment for fishing and a library. At the modern library, I could take a break and enjoy the latest magazines and books describing local culture. 
Hot spring day-trip
The bathroom at Fukuro Minshuku Inn was clean and cozy, but if you want to enjoy the Uraga Port view and a wider bathtub, Kuniga-So Inn offers a hot spring day-trip for 500 yen. After a long day of sea kayaking and fishing, I took a bath for my worn-out body to prepare for the next day’s exploration. 
Sample Itinerary
After arriving at Oki Airport, transfer to Nishinoshima Island by ferry and stay 2 nights if you want to enjoy Oki’s geological scenery. Next, head back to Dogo Island where you can find lots of activities including sunset cruises.
