The crew turns the Protostar into a sailing ship to cross a vapor ocean for fuel.
To restore power, the crew needs deuterium from a maelstrom on the far side of a vapor ocean, so they convert the Protostar into a makeshift sailing ship. Dal clashes with Chakotay before admitting he has been questioning his purpose since glimpsing his future through Wesley's portal. Chakotay offers advice drawn from his own experience, and Dal later saves him when he falls into the ocean.
The crew collects the deuterium, restores impulse and warp power and leaves Ysida, but Voyager-A is 3,000 light-years away, so they must build a new proto-core before the two ships can meet. The episode completes Chakotay's recovery from despair and gives Dal a mentor who understands the burden of command, while the voyage across the vapor sea gives the series one of its most unusual images, a starship under sail. Alex Hanson and Aaron J. Waltke wrote the episode and Sung Shin directed.