Taylor Swift -- Two Piece On the Button

The rumors are true ... Taylor Swift has a belly button and it's fantastic -- while you're more likely to see a white tiger than Swifty's middle ... miracles DO happen.

Those long legs are always out, but T-Swizzle has said she's not about showing off her tum-tum. Things change, and a few days back she felt comfy enough to rock a bikini in Maui.

Now that Taylor's launched her naval campaign ... everything has changed.