Cruise ship trip to cozumel!?

now, i'm not a fan of organized trips at all. im more of a "pack-a-backpack-good for three weeks-and go with the flow" type traveller. but this cruise was a gift, so i am gladly accepting! we are going to stop in cozumel for one whole day, with the ability to go and do whatever it is that we please to do. im a fan of wildlife exploration, but not a fan of paying more than my fare share of money, just to go on a hike! does anyone know of any must-see remote locations, or independent tour advisors that aren't ridiculously priced? i want to get the most out of my one day in cozumel! :)