- Japanese: 伊呂波丸 or いろは丸 (Iroha maru)
Iroha-maru refers to two different ships built in Bakumatsu era Japan.
The first was a three-masted Western-style sailing ship, constructed at Iso (in Kagoshima) in 1854, under the orders of Shimazu Nariakira. The ship was built as part of efforts by Nariakira to strengthen Satsuma domain's naval defenses in light of the number of British and French ships which had begun to visit the Ryûkyû Islands. In 1851, Nariakira had a shipyard built at Iso, measuring 100 meters long, 20 meters wide, and three meters deep. The three-masted Iroha-maru was completed at that shipyard in 1854, while another Western-style sailing ship, the Shôhei-maru, was completed the same year at another Satsuma shipyard at Setomura on Sakurajima.
A Western-style steamship by the same name was involved in a famous incident in 1867. This Iroha-maru steamship, under the command of Sakamoto Ryôma, crashed into a Kishû Tokugawa clan warship in the Inland Sea, just off of Tomonoura (a notable port in what is today Hiroshima prefecture). The Iroha-maru sank, and Ryôma famously engaged in negotiations with Kishû representatives, demanding reparations from them.