I saw a brief announcement of this in the newspaper the other day. There is a ferry from Tampa to Cancun and to Merida. The Yucatan Express is operated by Scotia Prince Cruises which has operated a luxury cruise ferry between Maine and Nova Scotia for 33 years.

Not much information on the website yet but see the latest press release on the site.

http://www.yucatanexpress.com/

Frances Toronto, Canada