Ukai is a traditional fishing method which uses trained cormorants to catch river fish such as sweetfish (ayu). This type of fishing has been around for over 1300 years, most prominently along the Nagaragawa River in Gifu City, where the master fishermen have official patronage from the emperor. Today, ukai takes place in the summer months in about a dozen rivers across Japan, including:

Ukai is practiced by master fishermen from long wooden boats. Each fisherman leads about a dozen cormorants on leashes who swim alongside the boat and dive under the water to catch fish by swallowing them whole. The fish are kept in a special pouch in the cormorant's throat to be retrieved later and are prevented from being swallowed by a snare around the bird's neck. Each boat carries a large fire to provide light for the boatmen to steer and the birds to fish by.

These days, ukai is held mainly as a tourist attraction. Special sightseeing cruises are offered that shadow the ukai boats and allow tourists to get an up-close look at the action. Details depend on each site, but the boats typically operate daily during the season except when the rivers have high water levels. Cruises typically last about an hour and cost around 2000 to 3500 yen per person.

Dinner cruises are also available at some of the ukai sites and provide a unique and popular way of experiencing ukai. Dinner cruises may be offered through the cruise companies themselves or through local hotels, ryokan and restaurants. Advance reservations are usually required. Alternatively, in many places it is also possible to watch the fishing action from along the riverbank for free.