Tanja sail or tanja rig is a type of sail commonly used by the Austronesian people, particularly in Maritime Southeast Asia. It is also known as the tilted square sail, canted rectangular sail, rectangular balance lug, or balance lug sail in English. In historical sources, tanja sail is sometimes incorrectly referred to as lateen sail or simply square sail.

Samudra Raksa is a replica ship built in 2003 based on the relief of ships in the Borobudur temple. In the late 20th century, Philip Beale, a British sailor, became interested in depictions of the ship at Borobudur and decided to reconstruct one. Aided by government and international bodies, he organized an expedition team that constructed the ship and, from 2003 to 2004, sailed it from Indonesia to Madagascar and to Ghana, proving that long-distance trade could have occurred. The Samudra Raksa Museum was constructed at Borobudur Archeological Park to house the ship, opening in 2005, and provides other displays to interpret the ancient maritime history of Indonesians.