Acid Rain



A hazardous substance found on the Space Pirate Homeworld in Metroid Prime 3: Corruption. Acid Rain falls in unshielded areas of the Homeworld and kills Samus almost immediately if she is exposed to it without the Hazard Shield. Acid Rain can also lull Samus into a false sense of security because it seems to affect Samus's energy very slowly. This, however, is not true because it takes Samus's energy at a faster rate as her energy meter falls. Eventually, the damage builds up to a massive rate where even with full energy tanks, her health is drained in seconds.

Logbook entry
Metroid Prime 3: Corruption: Acid rain is prevalent on the Pirate Homeworld, where the constant pollution has ruined the environment. The caustic effects of the rain are incredibly volatile and will severely damage your suit. Exposure to the rain for any extended period of time will prvoe fatal. Avoid all contact with the rain.

Trivia
Acid Rain also appears on Zebes in the Manga. However, it seems to be less potent as the physical adaptations Samus has gone through allow her to pass safely.