People with a fear of being in water rarely engage in water activities and hence miss out on the associated health benefits. Prior research suggested virtual exposure to treat fears. However, when it comes to a fear of being in water, virtual water might not capture water's immersive qualities, while real water can pose safety risks. We propose extended reality to combine both advantages: We conducted a study (N=12) where participants with a fear of being in water interacted with Fluito's virtual reality worlds while floating inside a floatation tank. Our findings, supported quantitatively by heart rate variability and qualitatively by interviews, suggest that playful extended reality could mitigate fear responses in an entertaining way.