The Submarine Combo (サブマリンコンビネーション Sabumarinkonbinēshon?, lit. "Submarine Combination") is a Tag Action in Sonic the Hedgehog 4: Episode II which allows Tails to carry Sonic underwater, like a submarine. This move is unlocked in Sylvania Castle Zone, Act 2.
Unlike its counterpart, the Copter Combo, the Submarine Combo has no actual limit, allowing Sonic and Tails to swim through the water until they exit the move by pressing the Tag Action button again. However, Sonic and Tails can still drown, and the two are vulnerable to damage from Badniks and hazards.
In Multiplayer mode, like Copter Combo, Tails' movement is controlled by his player.
- Using the Submarine Combo Tag Action, or any other Tag Action, while the player is using Super Sonic will revert Sonic back to normal.