Save Blackwater City is a mission in Up Your Arsenal, taking place in Blackwater City, Rilgar. While searching the Obani moons, just after meeting up with Skidd McMarx on Obani Pollux while exploring the moon, the Galactic Rangers sent a message to Ratchet and Clank about a tyhrranoid attack on Blackwater City. The two traveled to Blackwater City to help the Rangers, leaving Skidd to figure out the lock preventing them from accessing Obani's third moon.
To complete this mission, all three missions in Operation: BLACK TIDE must be completed. After completing them, the Rangers will provide the Gravity Boots. It is a good idea to complete the missions here before Holostar Studios, as the Gravity Boots allow you to obtain a titanium bolt on Holostar Studios without backtracking later.