Oxygen Supply Machines are devices in Mother 3. It is unclear who was responsible for their design, though their purpose is to supply oxygen to people traveling the sea route between Tazmily Village's beach and Tanetane Island. When Lucas and friends cross the Sea Floor Dungeon en route to Tanetane Island, they must use the Oxygen Supply Machines regularly to ensure that they will have enough oxygen continue progressing through the dungeon.
The machines themselves resemble mermen (possibly based around Aquarius of the Zodiac signs) with ridiculously oversized lips. To supply oxygen to the user, they lock their lips around the user's face and blow the oxygen into them. Lucas and friends slightly blush after using these machines.
The Oxygen Supply Machines are generally used by Navy SQUEALs of the Pigmask Army, who patrol the Sea Floor Dungeon. One of these soldiers actually claims to enjoy the process of receiving oxygen, much to the other's discomfort. An Oxygen Supply Machine can also be found near the end of the game in the Empire Porky Building, but takes the shape of a centaur (possibly based around Sagittarius of the Zodiac signs) rather than a merman. This one has no purpose, but will offer the characters some oxygen for "Old times' sake".