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I would not recommend seeing Tulum from Cozumel if you are traveling by ship - ship sponsored or not. At best, you will spend 75% of your time traveling. At worst, if it is not a ship sponsored tour, missing the ship from a tour that travels as from from the ship as this one does is a very real possibility. If you are going to do this, I recommend that you take your passport with you, you might need it. My recommendation for seeing Tulum is to see it when you are staying in a hotel in Cancun.
I would not recommend seeing Tulum from Cozumel if you are traveling by ship - ship sponsored or not. At best, you will spend 75% of your time traveling. At worst, if it is not a ship sponsored tour, missing the ship from a tour that travels as from from the ship as this one does is a very real possibility. If you are going to do this, I recommend that you take your passport with you, you might need it.
My recommendation for seeing Tulum is to see it when you are staying in a hotel in Cancun.