This is what nightmares are made of:
Imagine hearing a Geiger counter's crackly protests as you slowly descend, the water getting hotter and hotter. A burning sensation starting on your skin as the beta-particles chew through your DNA with carcinogenic fury. Nausea and migraines pummeling your body as you alight on the bottom of the pool, your ability to produce viable children immediately compromised.
Don't worry, it wouldn't last long.
Keep treading water, you guys.