The Hydora Campaign takes place on the planet Hydora which is almost entirely covered by water.
Episode 6 "Water, Water Everywhere" Hydora: Day 1
The Campaign began when SICON forces consisting of 10 Starships including the Valley Forge were sent on a mission to track down the Arachnid Transport Bug which had escaped from Pluto. The fleet was able to track down the Transport Bug to the planet Hydora inside the constellation Virgo.
SICON orders The Roughnecks to watch the Transport and see if it has returned to the Bugs' Home Planet...or if Hydora is some kind of 'Grand Central Bug Station'. When a new type of bug known as Ripplers exit the Transport, Razak, Dizzy and Brutto follow the new arrivals; the rest of the squad conducts surveillance on the Transport Bug. When this surveillance group comes under attack by Ripplers, Doc and Gossard get stranded on the side of a cliff ... Rico, Carl and Higgins get trapped inside the Transport Bug. As they try to get out of the Transport, Carl receives a psychic message from the Bugs. Eventually, the Roughnecks regroup and report to SICON that this is not the Bugs' Home Planet. Then Carl reveals the message he received inside the Transport - the Bugs want them to know that they won't stop until every human being, everywhere, is destroyed.
Episode 7 "Swarm" Hydora: Day 28
Carmen is stranded on Hydora while rescuing Troopers injured in a fierce Bug battle. She teams up with Lt. Bernstein, the commander of Zebra squad, now in charge of a makeshift group of Troopers from several different squads. When they become trapped by a new aggressive strain of Ripplers known as "Kamikazes," Razak's Roughnecks come to the rescue. Word comes from S.I.C.O.N. command that these Kamikaze Ripplers are swarming across the planet, preventing supplies and reinforcements from getting in. Bernstein and his men, and Razak's Roughnecks take part in a two-pronged battle plan -- eliminating the Kamikazes from underground hide-outs, and driving the remainder up top, where Snipers are waiting to take them out. Meanwhile, Rico is surprised to see Carmen ... and risks his life and every one else to try and impress her.
Episode 8 "Search & Destroy" Hydora: Day 30
The Roughnecks are sent into enemy territory to search for a Rippler nest and destroy it. Razak decides to split the Roughnecks into two groups - Brutto is put in charge of one group, consisting of Rico, Carl, Higgins and Doc; while Razak takes Dizzy and Gossard. Brutto's group faces massive enemy threats along the way, and Carl is severely injured. Rico and Doc want Brutto to break radio silence and notify Razak about Carl, but Brutto refuses. Then, their boat winds up destroyed in a whirlpool. Everybody survives, surfacing in a grotto where they're picked up by Razak. Rico and Brutto come to blows over not contacting Razak -- but the argument is cut short when the Roughnecks finally discover the massive egg sacks, and Adult Ripplers arrive to defend the babies. Rico saves Brutto's life ... and eventually, the squad must blow up the grotto with a huge explosion -- which they must outrun in order to live. Later, because Rico and Brutto have bonded, Rico covers for Brutto. Razak is skeptical ... but lets it drop.
Episode 9 "Missing In Action" Hydora: Day 40
The Roughnecks are sent down to Hydora to find two squads that have vanished into thin air. On the way, Rico and Dizzy bicker when he criticizes her for taking too many risks. During the search and rescue operation, Dizzy races off on her own to battle Water Tigers -- large amphibious beetles with giant pincers -- and Rico turns his back on her for a split second. Dizzy also disappears, and Rico is devastated, blaming himself. The Roughnecks eventually track Dizzy and the other missing troopers to the Water Tigers' lair, where the MIA's have been entombed in hive chambers. Dizzy and the others are rescued, revived with an anti-venom, and everyone races to get out of the underground lair, with Water Tigers giving chase. Razak eventually nukes the place...and Rico, who has been going overboard trying to take care of Dizzy, is eventually told by her to knock it off -- she likes him better as a jerk.
Episode 10 "Sole Survivor" Hydora: Day 112
The Roughnecks discover Lt. Ross, commander of Delta Squad, wandering on Hydora, his long-term memory wiped out, and his entire squad missing. The Roughnecks are sent on an investigative mission to discover what happened to Ross and his men, while Carl is told to perform a mindscan on Ross, unlocking his repressed memories. Rico has a problem with Carl invading a man's mind, and tells Carl that if he's ever in trouble, to stay out of his head. On Hydora, the Roughnecks wind up captured by Warrior Bugs and taken to a cavern, where the Brain Bug that controls the entire planet plans to mind probe the entire squad, starting with Rico. Back on the Valley Forge, Carl discovers this is what happened to Ross and his men. He tries to send Rico a psychic warning, but it is too late ... and Carl races to Hydora with a group of Troopers to save his squad from a horrifying fate. Carl has a psychic, telekinetic showdown with the Brain Bug, blowing it up with a mindbomb. Later, Carl reveals there are more Brain Bugs on every planet the Bug Army has invaded, and the war is far from over. Rico and Carl come to an understanding about his powers ... later it is learned that the confrontation with the Brain Bug has hurt Carl, which he hides from the others.