We primarily just walked around the city. Did not do any excursions. We noticed trucks driving around with soldiers carrying machine guns. A bit disconcerting, but nothing to get too concerned about.
We took the city bus to and boardwalk, which is about 10 miles away from the port. Its a nice area, but a bit touristy. It was nice riding the bus and getting a favor for the Mexican culture. It only cost about $1 per person to ride the bus (which is probably not like the bus you are used to riding at home). People were very friendly and willing to help us get to where we wanted to go.
This was our favorite port. We took a water taxi around the harbor. We got a chance to see some dolphins pretty that were pretty close, also saw tropical fish in a glass bottomed boat and Lover's Beach. We then took a Bicycle tour of the city.
This was our least favorite port. We took a tour to the Blow Hole, which was okay, but nothing out of the ordinary. If you have seen the one on Oahu, this one pales in comparison. There is a large flea market at the blow hole, which is great for buying souvenirs.