Garn

I'm not sure what you're looking for, but it seems like the options are fairly limited for tours. While I prefer private tours myself, you might want to consider one of Terry's group tours, since there's quite a bit of variety between them... but I don't have my tour with him for another couple of weeks so I can't personally vouch for the quality.

Just because I'm nerd enough to wonder, I looked them both up in Merriam-Webster online. It looks like both are old terms, with the origin very much tied to ships as opposed to other forms of transportation (not that there were many other vehicles at the time)

Debark:

Etymology:French debarquer, from de- + barque bark (ship)Date:1654

Disembark:

Etymology:Middle French desembarquer, from des- dis- + embarquer to embarkDate:1582