"Chicoutimi" cleared Faslane on 4 October 2004 on her homeward journey to Canada. Since Faslane was a nuclear submarine base, "Chicoutimi" was forced to travel on the surface for the first stage of the passage. On 5 October "Chicoutimi" was passing through a gale with seas. During a watch change at 0300 sea water entered the conning tower. The lower hatch prevented the water from entering the sub; however, the drain in the tower failed to operate. When the lower hatch was opened, the water fell into the sub. However, the water was pumped overboard and the incident noted. The drain valves required repair before diving. At 1052 two crew entered the tower to perform repairs. The upper hatch was opened. However, after roughly 25 minutes, another tool was needed from within the sub. When the lower hatch was opened, the submarine was rocked by a large wave, throwing roughly 500 gallons of sea water into "Chicoutimi". Electrical explosions and fire erupted soon afterward, spreading quickly. In order to fight the fire, all systems aboard the submarine were shut down, leaving the submarine dead in the water. An attempt to restore auxiliary power caused another fire to break out. At 1912, attempts to remove smoke by starting an oxygen generator caused another fire. Nine sailors were injured, three seriously.