We used the Mears Shuttle to go from CSR to Seaworld last February and it was really easy. I think we scheduled a time for pick up at least 24 hours in advance. They picked us up in front of CSR and we made one other stop on the way to Seaworld. Mears will pick up at Seaworld at scheduled times throughout the day, you just need to call them a couple hours in advance to let them know what time you want to leave.