The Redwood Coast Tsunami Work Group at Humboldt State University reported the remains of a 21-foot skiff bearing several numbers and Japanese writing was found about a mile north of Crescent City.
Handwritten characters on the side of the boat translated to "Takada High School," a high school in Rikuzentakata city -- one of the places hit hardest by the 2011 tsunami, researchers said.
"There's no question that the boat is Japanese," Lori Dengler of the tsunami group said. "And that school puts it right in the tsunami zone."
Researchers with the group plan to test whether the gooseneck barnacles encrusting the top and sides of the boat are native to the Western Pacific waters around Japan.
The earthquake and tsunami that devastated Japan in March 2011 dumped some 5 million tons of debris into the Pacific Ocean, of which about 1.5 million tons were set adrift, researchers said.
The National Oceanic and Atmospheric Administration, which collects and verifies reports of tsunami debris, says 25 large items have been confirmed as definite tsunami debris, the Eureka (Calif.) Times-Standard reported.