Nibiru

A forest world, Nibiru also boasted several large lakes. Princess Leia's crashed in a lake on the planet after the Battle of Hoth. Leia was tended to by the friendly Ewoks on the planet. Luke Skywalker retrieved a data cube with Imperial battle plans from the ship and returned the cube to Leia, whom gave the cube to Mon Mothma.

Behind the scenes
It is likely that Nibiru is based on Nibiru, a celestial body that the ancient Babylonians associated with the god Marduk.