Metall Swim

Metall Swim (メットールスイム) is a Met model from the original Mega Man series that can work underwater, being equipped with flippers and a snorkel. Swim Metalls bob up and down to swim toward Mega Man while shooting. They are immune to damage while hiding under the helmet, but otherwise one shot is enough to take them down. It appears in the underwater areas at Dive Man's stage in Mega Man 4 and Mega Man III, in the first Wily Castle stage in Mega Man 4, in the second Wily Castle stage in Mega Man 5, and in the Met race from Wily & Right's RockBoard: That's Paradise.

Swim Metall DX
Swim Metall DX (スイムメットールＤＸ) is a deluxe version of the Metall Swim that was modified to be able to work freely with chemicals. It appears in Burst Man's stage and the third Wily Castle stage in Mega Man 7.

Swim Metall RW
Swim Metall RW is a variation in the first three games of the Mega Man Zero series. It only appears if Zero uses a Met-like Cyber-elf, which will replace most aquatic enemies by a Swim Metall RW. Those Mets act like the Swim Metall DX from Mega Man 7.

Other media
Metall Swim appeared in the Rockman 5 manga, and Swim Metall DX appeared in the Rockman 7 manga.