Sea Mine, also known as Cray (キライ,Kirai?) is a mine in Mega Man 4. They only appear in Dive Man's stage, appropriately enough. They bob up and down, and are invincible to attacks. They explode after a short while when Mega Man draws near.
In Mega Man 2: The Power Fighters, Sea Mines are blue instead of red as they are produced by Dive Man's body. A weapon could destroy them.