Phase 5 is the middle stage of the three red phases in Balloon Fight.
There are six floating platforms, each holding a Balloon Bird. The top platform is flat, and holds one yellow Balloon Bird. There are three spike-like platforms placed halfway up the stage, and each holds a green Balloon Bird. There also two small, flat platforms that float low over the water, and each have a pink Balloon Bird on top of them. There are also two Clouds, one to the left of the highest platform, and another above and between the right and the center spike-like platforms halfway up the screen.
- After Phase 12, this phase will be repeated. In later rounds, this will appear as Phases 14, 23, 32, 41, 50, 59, 68, 77, 86, 95, A4, B3, C2, D1, E0, E9, F8, G7, H6, I5, J4, K3, L2, M1, N0, N9, O8, and so on.
- This stage has a slight oversight in it, as the middle spike-shaped platform has its collision area extended to the right slightly too far, allowing for the player and the enemies to land seemingly on top of nothing. This is made possible because each stage's collision is stored separately from the actual stage graphics data. It is possible that the middle platform may have been larger at some time, though the collision was not changed to match, but this can't be confirmed.