The largest craters in Elysium Planitia are Eddie, Lockyer, and Tombaugh. The planitia also has river valleys—one of which, Athabasca Valles may be one of the youngest on Mars. On the north east side is an elongated depression called Orcus Patera, and this and some of the eastern plains were imaged in the 1965 Mariner 4 flyby.