They offer the Tulum tour on some of the ships that go to Cozumel. Its a 8 hour long tour and your ship is probally not there long enough. We have been to Cozumel twice, they have offered it both times, but we were there until late into the night.
We booked the Tulum tour while on board the Inspiration. We made it back to the ship by 5PM with no problem. The ferry ride was only about 25 mins from Coz. to Playa del Carmen and then about an hour bus ride to Tulum. Bring a bathing suit because there's a great beach at the Mayan ruins in Tulum. It was a great tour and well worth the time and effort.