A simple belt that keeps Donut from sinking in water — which she loudly insists she'll never need again.
The Belt of Buoyancy is the bonus item Princess Donut receives from her (inexplicably silver) 'I'm Wet' box after the water-quadrant ordeal. A simple belt that wraps around her stomach, it keeps her from sinking — but only works in water. Donut spends a good three minutes complaining about it, insisting she is never going back into the water again, making the gift a pointed little joke at her expense.
A simple belt worn around the stomach; functions only while submerged.
Donut's anti-sinking water gear — a mockery of her hydrophobia.