in December? I've been to Maui in March a couple times but I hear it's about 70 degrees in January. Anybody with first hand experience?

The water is ALWAYS warm enough for swimming in Hawaii !!

yes, Rusty is correct!

I have never had a problem with winter waters in Maui. Once we spent 3 weeks on Kauai in January and it was overcast for a few days running. That cooled everything down quite a bit and the water just seemed colder too (probably just our perception) I was actually surprised at how warn the water actually is in the winter months the first few times I swam!

The ocean water near Maui averages 76 degrees (F) in December, according to hawaiiweathertoday.com

It depends what you like. It gets cold to me.