The Sandwich Island:  

Twain sailed from San Francisco aboard the Ajax on March 7, 1866, arriving in Honolulu 11 days later.

He went to the island of Maui April 14, 1866 ands studied sugar plantations.

Returned to Oahu May 22, 1866 for four days and attended the legislature.

May 26, he sailed for the big island of Hawaii aboard the Emeline, known as the Boomerang. He landed at Kailua, on the Kona Coast, two days later then sailed down the coast to Kealakekua Bay the next day.  He disembarked the Emeline at Kau June 29, and traveled by foot to Kilauea and Hilo, arriving June 8.  He contined on foot and horseback to Kawaihea, from which he returned to Oahu on June 15.

Twain remained on  Oahu until July 19, 1866 when he sailed aboard the Smyrniote for San Francisco, arrvinf there August 13, 1866.