scene, a sailor falls overboard into a sea of accurately rendered pancake ice. In another scene, Captain Francis Crozier sees a sun dog—a solar phenomenon caused by sunlight refracting through clouds of ice crystals, often witnessed by polar explorers. The officers' uniforms and caps are also recreated with authentic details. As the hopelessness of their predicament dawns on the officers and men, summer’s 24-hour daylight vanishes, replaced by the 24-hour darkness of winter. The imprisoned ships tilt with the pressure of the pack ice.

There were a few hiccups noticed by sharp-eyed viewers in the Remembering the Franklin Expedition Facebook group, however. Caulker's mate Cornelius Hickey has a fondness for cigarettes, but most sailors probably smoked pipes at the time, and definitely not inside the ship. (Good thing theymasquerade party in the middle of the bleak and frozen Arctic, which Fitzjames orders as a morale-booster for the men in Episode 6, may seem like a total anachronism. In real life, it was a time-honored tradition. (We don't know for sure if the Erebus and Terror had a carnival because no logbooks from the expedition have been found, but it's likely that they did.) In 1819-1820, Sir Edward Parry led the first polar expedition to purposefully overwinter in the Arctic. He worried about how the men would fare psychologically during the months of darkness and teeth-cracking cold, so he brought along trunks of theatrical costumes and launched the Royal Arctic Theatre, a fortnightly diversion for the officers and men to perform silly plays and musicals. It kept