Renewing visa with a cruise.

I was thinking of taking a cruise out of Jaco for a visa run. Has anyone ever done this? Does it actually give you another 90 days, even if all the ports are in Costa Rica?

If you are not exiting CR, entering another country, then re-entering CR, I doubt whether a cruise would accomplish this. You should check directly with the 'cruise line' and/or immigration. Plus, there is no guarantee that you will be given an additional 90 days.

How is going to stamp your passport to give you another 90 days?