Vagabundo is right that there isn't a whole heck of a lot there. Its not like Cabo or anything. Cancun proper is pretty dry on charter boats unless you want to catch barracuda all day (yawn). Been there, done that. HOWEVER, Isla Mujeres is a 20 minute ferry ride across and holy smokes man, you are going to be there when the sailfish bite is off the hook! As a matter of fact it will be prime time. It is truly world class and its a bucket list trip for sure. Read the link from Marlin Magazine below. I also included another link to a charter company that looks like they are based out of Cancun. I've only used charter boats out of Isla Mujeres. Good luck and make it happen. Let me know how it goes if you go. We caught and tagged 12 sails and lost another handful the day I went 3 years ago. If you do go (and you really should) you've got to let me know how many you released.
I will be in Cancun Oct 7th to the 15th. Have a boat chartered for 6 hours lunch permits beer tackle etc 500.00 for 6 hours for 1 to 8 people. Let me know if anyone is going to be there at the same time. fishing Oct 12