If you are doing a Western Caribbean Cruise you are likely to stop at Costa Maya. One of popular half day tours offered by your cruise ship is a visit to the Mayan Ruins of Chacchoben. This is apparently a wheelchair and push chair accessible site so maybe a good option for those with accessibility issues – though the ground is very uneven.
The site has only been open to the public since 2002. There are a handful of step pyramids, walls and staircases. Parts of the ruins are still covered in jungle, still yet to be excavated.
Human settlement has been in the area since around 1000BC so its a glimpse back potentially 3000 years, though most of the ruins are around 1500 years old, dating from around 300-360AD.
Although there is apparently some wildlife in the area, the only animal we saw was the Coatimundi in the last picture.
For more information about visiting, this FAQ from the company that run the ships tours may be of interest.