Any advice on good excursions off ship in Cozumel ? Thinking about sailing on yhe American Cup boat Stars and Stripes. Has anyone done this? Thanks for any help.

We went to Tulum and loved it.

The American Cup challenge is great if you are physical able and do not have motion sickness. You are an active participant and you are part of the "crew". It's great fun if you enjoy sailing and those type of activities. This is a knock off (or actually operated by the same company?) of the sailing challenge at St. Marten.

This is another vote for Tolum. Even though the town center sits right on the highway, you may want to get to the coast a bit more if you are interested in the tropical paradise feeling. You can get one of the best beaches in Mexico, a variety of lodgings and restaurants to fit every budget, great snorkeling, don’t forget the Maya ruin.

Is a vist to Tulum achievable as a day trip from the cruise ship from Cozumel?

You will need an early start but yes you can, depending on how long the ship is in port. I would think the ship has excursions to Tulum and I too recommend it.

Make sure you get the ferry schedule and give yourself enough time and not catch the one just making it. 1/2 hour to 45 minutes ferry ride and then about an hour by vehicle. It would be at least 2 hours of commute each way leaving you with whatever time left (typically about 4 to 5 hours) to explore the site and the beach adjacent to it.

If you have never been there, it's worth a visit. The site is so popular that they have robed off most of the building so you can no longer get too close or climb to the top of the temple.

Coba is less crowded and further away but you can still get to the top of the temple for a panoramic view.