Steel Diver

The Steel Diver is a long-range projectile weapon/item introduced in Super Smash Bros. for Nintendo 3DS / Wii U and reappearing in Super Smash Bros. Ultimate. This weapon is based off the appearance of the Blue Shark submarine from Nintendo's Steel Diver game for the Nintendo 3DS. It launches hard-to-see torpedoes, that start out slowly before they speed up and explode upon contact with an opponent, an item or if they reach their maximum distance.

Super Smash Bros. for Nintendo 3DS / Wii U trophy information
Blue indicates exclusive to the Wii U version.