HM03 (Japanese: ひでんマシン０３Secret Machine 03) is an HM introduced in Generation I. It teaches a compatible Pokémon a move that can also be used in the field; but using an HM in the field requires that the player have a certain Badge (except in Generation V). HM03 has always been Surf. For compatibility, refer to the move's page. HMs can used to teach moves without limit.
HMs in the Mystery Dungeon series are named only by the move they teach. For example, Cut is the item that teaches the move Cut. Most HMs, however, correspond to an HM in the core series' contemporaneous games.
HMs in Pokémon Mystery Dungeon games prior to Pokémon Super Mystery Dungeon can be used any number of times. In Pokémon Super Mystery Dungeon, "HMs" are treated like TMs and only usable once. However, if an "HM" is dropped on the ground, it has a different color than a TM.
In What a Dragonite, Red tried to get his hands on HM03 (Surf), but ran into some trouble with a wild Dragonite, eventually leading to the Hidden Machine getting destroyed. To help him, Misty gave Red her Gyaradosin exchange for his Krabby, since it already knew Surf.
It was also revealed that Blue had found HM03 before Red, fueling the young Trainer's determination of finding it too.
Cut is the item that teaches the move Cut. Most HMs, however, correspond to an HM in the core series' contemporaneous games.
