Optimal Health

The cure comes from the Sea Emperor's children. In the Primary Containment Facility (Fourteen Thousand Leagues Under the Sea), the Emperor sets you the errand: gather the ingredients for the hatching enzymes (she points you to each - all obtainable in the nearby biomes), cook them at the facility's incubator console, and hatch her eggs. Swim with the hatchlings and collect the Enzyme 42 they shed - your infection clears, the achievement pops, and the gun on the Enforcement Platform will finally let you leave (Go Among the Stars).