The Profundity was an MC75 Star Cruiser commanded by Admiral Raddus that served in the Alliance Fleet. It was notably present during the Battle of Scarif. Shortly after the Death Star plans were transmitted to Raddus, the vessel was incapacitated by the Star Destroyer Devastator and boarded by Darth Vader in an attempt to reclaim the stolen data tapes.
As the Dark Lord stormed the corridors of the starship, a small group of Rebel troopers were able to evacuate on board the Tantive IV, which had been docked with the Profundity, relinquishing the plans to Princess Leia Organa.
Raddus and a rebel trooper on the bridge of the Profundity discussing Rogue One
Originally, the Profundity was the civic governance tower of the city of Nystullum. Like many Mon Calamari buildings, the tower was converted into a ship and was part of the exodus fleet that departed from the Mon Calamari homeworld under command of Raddus, the city's mayor. Many of the ships crew members where former defense staff for the city of Nystullum. When the Mon Calamari joined the Alliance, the Profundity was one of the first ships to be converted into a warship. When Rogue One's departure for Scarif became known, Admiral Raddus gathered as many ships as he could to support them. After the Alliance Fleet arrived at Scarif, the Profundity took part in the battle, acting as the command ship for the Alliance's forces.
As the battle concluded, the Profundity intercepted the Death Star plans beamed to the ship by Jyn Erso of Rogue One. Before the cruiser could depart with the prize, it was incapacitated by the Devastator and boarded by Darth Vader in an attempt to recover the plans.
Vader and his forces prepare to board the damaged Profundity
A few Rebel troopers from the Tantive IV managed to download the plans to a data tape and attempted to make their escape to the ship in the Profunditys docking bay. Just as the Rebels reached the door, however, a mechanical failure caused by damage jammed it. A few moments after the door jammed, Vader arrived in the hallway. The rebels held Vader off for as long as they could until one trooper was able to pass the plans through the gap in the door to their fellow crew on the ship. The corvette quickly launched from the vessel, leaving Vader standing in the bay. By the end of the engagement, the Profundity was destroyed.
The Profundity first appeared in Rogue One: A Star Wars Story directed by Gareth Edwards and was first named in Star Wars: Rogue One: The Ultimate Visual Guide by Pablo Hidalgo. In early concept art, it was referred to as the "Rebel trawler." An adventure and encounter seed in Starships and Speeders, a 2020 sourcebook for the Star Wars Roleplaying series by Fantasy Flight Games stated that the Profundity was found intact, and that the Empire sought to use it as a target in a weapon testing range.