Returned several weeks ago from an amazing trip to Misool Eco Resort armed with my tiny Sony RX100 and Nauticam housing. I love this combination and my only regret was spending money on a macro dioper and strobe and not a wide angle diopter and the latest Light and Motion video lamps. That not withstanding I captured some pretty reasonable footage (IMHO)
Take a look at this sample of mantas captured on Misool's famous 'Magic Mountain'
Original format AVCHD 1920x1080p 50fps, subsequently converted to Apple ProRes and edited in FCP. No post production colour editing.