The central caldera is nearly 56 km across . Like Biblis Patera, Ulysses Patera is surrounded by younger lava flows. It is also cut by a few graben. The most striking features on this volcano, however, are two large impact craters. These craters overlap the caldera and clearly postdate all major volcanism at this site.
Large craters are rare outside of the cratered uplands on Mars.
Thus, the presence of two such craters on Ulysses Patera is highly unusual. This volcano appears to be very old.