Oberon and Titania

The two largest moons, Oberon, 942 mi (1,516 km) in diameter, and Titania, 982 mi (1,580 km) in diameter, are less than half the diameter of Earth's Moon. Titania, the reddest of Uranus's moons, may have endured global tectonics as evidenced by complex valleys and fault lines etched into its surface. Smooth sections indicate that volcanic resurfacing has taken place.

Umbriel and Ariel