Nyuto Onsen is a collection of onsen ryokan in the mountains of eastern Akita Prefecture. The area is known for the hot spring baths found at its eight ryokan, some of which are quite traditional and rustic. With a history of over 300 years, Tsurunoyu is Nyuto Onsen's oldest and most famous inn.

The name Nyuto Onsen means "nipple hot spring" and comes from the suggestive shape of nearby Mount Nyuto rather than the milky/cloudy appearance of the area's hot spring water. All the hot spring baths in Nyuto Onsen belong to ryokan, and are not only available to staying guests, but also to day trippers during certain hours and against a small admission fee. Most of the ryokan feature mixed gender outdoor baths, and all have various gender segregated bathing as well.

Part of the Towada-Hachimantai National Park, Nyuto Onsen is a 30 minute bus ride into the mountains above the picturesque caldera lake Tazawako, the deepest lake in Japan. A few other hot spring towns and hiking trails are also found in the area around Tazawako and Nyuto Onsen.