I told the merchant I had a Groupon voucher and they asked for the barcode, scanned it, then gave me our passes. Super smooth! They weren't very busy so within 5 minutes we were on a boat. The kids and adults in our group loved it. The water was so much prettier than I expected. We come to San Marcos so much to visit family and somehow this was our first time going. The captain of our boat was so knowledgeable about the plants, animals, and aquifer. We will 100% be back.