Do you mean Tulum or ruins on the island of Cozumel? Tulum is a 45 minutes ferry ride to the mainland, then about a 45 minute bus ride south to Tulum. We were thinking of doing the excursion on our own, but with the possibility of getting back late and missing the ship (AND leaving our DD3 and DD5 in the care of my MIL!!!!,) we decided to do the ship's excursion. We left the ship as soon as we landed (around 9:30) and got back to the ship at 5:20. We left the port at 6:30.