KUNA VELA. Sloop rigged sailboat based in Cocos. www.kunavela.com
Any one of these fine companies will give you a sailing adventure. It all depends on what you are looking for of course. The big boats are day sails with lots of customers while the smaller boats can be custom chartered for your specific needs.
All do a fine job and are fully licensed by Costa Rican authorities with certified Captains and crews.